This guide describes some of the various radio receivers used in 60's, 70's, and 80's Chevrolet cars and pick-up trucks. GM offered numerous radio, stereo, and tape player options over the years so it is nearly impossible to compile an all inclusive list. Shown here is simply a listing of some of the more common shaft spacing and dash opening sizes along with some common electrical connectors found throughout this year range.



Shaft Spacing, Center Opening Sizes, and Example Photos

6 14" shaft spacing with 4 12" x 1 916" center opening

Some vehicles using this size radio include:

Example: Model #986771 AM manual tune radio used in 1966 Chevrolet trucks.
Example: Model #985432 AM pushbutton radio used in 1963 Chevrolet passenger cars.
This particular example is shown with the optional front/rear speaker fader control.
Example: Model #985877 AM/FM pushbutton radio used in 1964 Chevrolet passenger cars.

Note: Both car and truck applications feature a recessed area cast into the face plate around the RH tuning knob shaft. This area is unused on truck radios and has a fairly long mounting collar around the RH shaft that extends all the way out to the dash (where it is secured with a nut). Car radios make use of the recessed area to accommodate an optional front/rear fader control used for a rear speaker. Therefore, the car radios have a shorter mounting collar around the RH shaft. The cutout in the car dash opening has a larger hole on the RH side for the special cupped mounting washer used in conjunction with the shorter/recessed collar.

Comparison of car vs. truck radio mounting differences.

There are also some diffences in the bottom/rear mounting support on the car vs. truck radios in this year range. The car radio has provisions for a support bracket to attach to the bottom cover plate. While the truck radio uses a mounting bracket attached to the rear of the case.


6 14" shaft spacing with 4 12" x 1 34" (or 1 1316") center opening

Some vehicles using this size radio include:

Note 1: The center portion of the faceplates on these radios are slightly larger than the dash opening. That is because they are designed to have the faceplate fitting up against the back of the dash (instead of fitting through the center opening).

Note 2: The coloring of the lens changed from green to blue sometime around 1971 for most models. The '74 example shown above has an incorrect earlier green lens.

Note 3: The 1969 versions of these radios used a different electrical connector than the 1970+ ones. See the Electrical Connections and Common Wire Color Codes section for details on the wiring changes.

Example: #41XPB1 pushbutton AM mono radio used in 1974 Novas & Camaros.
Note that this particular example has an incorrect older style lens with the green band at the top. 71-up were originally blue to match the instrument cluster.

Example: #60XFPK1 pushbutton AM/FM mono w/fader used in 1976 Novas & Camaros.

6 14" shaft spacing with 4 12" x 2 14" center opening

Some vehicles using this size radio include:

Example: #01TPB1 pushbutton AM mono radio used in 1970 Chevy trucks.

5 34" shaft spacing with 4 14" x 2" center opening

This radio size was introduced in 1973 and by the late 70's to early 80's it had become the GM corporate standard for most trucks and rear wheel drive cars. The GM service & repair literature often refers to these as Delco 2700 series units.

Some vehicles using this size radio include:

Note: This list is grouping these radios according to the knob spacing and center hole dimensions only and does not take into account the wiring change that took place in 1978. See the Electrical Connections and Common Wire Color Codes section for details on the wiring changes.

Example: #31BPB1 pushbutton AM mono radio used in 1973 Chevy full-size cars.
Example: #60HFM1 pushbutton AM/FM stereo used in 1976 Chevelle, Monte Carlo, Vega, Monza, & GM trucks.
Example: #30BCCS1 pushbutton AM/FM stereo with cassette player used in 1983 Chevy full-size cars & trucks.
Example: #16034753 ETR (Electronically Tuned Receiver) AM/FM stereo with cassette player used in 1987 GM truck, Van, Blazer, & Suburban.

Note: The center portion of the faceplates on many of these radios is taller (and a little wider) than the actual dash opening. That is because they are designed to have the faceplate fitting up against the back of the dash (instead of fitting through the center opening).

Electrical Connections and Common Wire Color Codes

Socket on Back of Radio Corresponding Connector(s) Connector Pin-out Diagram

The 3 terminal radio socket shown above is used on many 1963 & newer Chevy cars and trucks with mono AM or AM/FM radios. I believe it continued to be used in cars until 1968 and pickup trucks until 1972, possibly beyond that in some applications.

The 3 terminal plug that fits these radios is part of the speaker harness and uses Packard 56 series female terminals on the speaker wires. The power wire connection uses a special extension or "piggyback" terminal with a female end that plugs into the radio and a male end that accepts a single-terminal power wire connector from the vehicle. On most cars, the power wire is part of the dash harness. On most pickup trucks, the power wire is a separate wire that simply plugs into the fuse box and runs over to the radio.

On cars equipped with a rear speaker, a second sub-harness (with matching 3-terminal plugs) is jumpered in between the radio and front speaker harness. This sub-harness connects to a fader control (that slides over the RH tuner shaft) and is used to divide the radio's single speaker output between the front and rear speakers.

Wire color codes for this style of radio connector varied, but the most common are:

  • Radio ground = chassis/case ground
  • Switched +12V feed to radio = brown, yellow, black w/yellow stripe, or red (this also powers the dial light when the radio is on)
  • Front speaker positive & negative = light green & black zipcord
  • Optional rear speaker positive = white or black
  • Optional rear speaker negative = chassis ground

1969 radios use a connector that is unique to this year. Sorry, no photos or diagrams for this connector yet.


Socket on Back of Radio Corresponding Connector(s) Connector Pin-out Diagram

The 6 terminal radio socket & plug shown above is used on 1970 - 1976 Novas and Camaros & 1970 - 1972 Chevelles with AM or AM/FM mono radios. The 6-terminal plug that fits into the back of the radio is part of a speaker/jumper harness. It uses Pack-Con female terminals. The jumper harness also includes a 3-terminal power/light/ground connector that uses Packard 56 series terminals and plugs into a mating connector that is part of the car's dash harness.

Wire colors for the speakers sometimes vary, but for the most part they tend to be standardized to:

  • Radio ground = black (radio case is also ground)
  • Switched +12V feed to radio = yellow
  • Dial light = gray
  • Front speaker positive = light green
  • Optional rear speaker positive = dark blue
  • Speaker negative (front & rear) = black or black w/double white stripes
Socket on Back of Radio Corresponding Connector(s) Connector Pin-out Diagram

The 10 terminal radio socket shown above is used on many Chevy cars starting in 1971. Exceptions include 71 & 72 Chevelles, and 71 through 76 Novas & Camaros which used the 6 or 9 terminal connectors shown above. Novas & Camaros used this 10 terminal style for 1977 only. It was also used in 1973 - 1977 GM pickup trucks, Blazers/Jimmys, and Suburbans.

The socket is divided into three sections, each of which accepts a plug that uses female Pack-Con terminals. The 3-terminal power/light/ground plug is part of the under-dash harness and the wire color coding on this is usually:

  1. Radio ground = black (radio case is also ground)
  2. Switched +12V feed to radio = yellow
  3. Dial light = gray

The 4-terminal and 3-terminal speaker plugs are part of the speaker harness(es) and the wire color coding depends on the particular radio and application. Not all wires/terminals are used for single speaker and front/rear mono applications. The speaker harnesses on some 2-speaker stereo setups ran one speaker off the front, the other off the rear, and used 5 foot sections of 2Ω-per-foot resistance wire (10Ω total) to take the place of the other two speakers.

Some 1976 & 77 stereo radios use a very similar looking 11 terminal connector (not shown). Those have a 4-terminal (instead of 3-terminal) connector for the rear speakers; giving each rear speaker it's own ground/return wire.

Some of these radios featured a digital tuner and clock display. These will have an additional 2-wire pigtail/socket on the back with orange and brown wires that are connected as shown for the following style.

Socket on Back of Radio Corresponding Connector (s) Connector Pin-out Diagram

The 12 terminal socket shown above is used on nearly all GM radios/stereos/tape players from 1978 up into the early 1990's (certain models). The socket is divided into three 4 terminal sections (power, front speakers, and rear speakers). Radios with digital tuners / clocks have an additional 2 terminal connector. The wire colors on these connectors seem to be standardized to:

  • On the 4-terminal black connector:
    1. Power antenna (optional) = pink
    2. Switched +12V power = yellow
    3. Radio ground = black (radio case is also ground)
    4. Dial light or digital display dimmer signal = gray
  • On the 4-terminal white connector:
    1. RF Speaker + = light green
    2. LF Speaker + = tan
    3. RF Speaker - = dark green
    4. LF Speaker - = gray
  • On the 4-terminal blue connector:
    1. LR Speaker + = brown
    2. RR Speaker + = dark blue
    3. LR Speaker - = yellow
    4. RR Speaker - = light blue
  • On the 2-terminal black connector (digital tuner/clock only):
    1. +12V constant battery power = orange
    2. Lights on signal = brown

Not all radios with this style of connector make use of all the available connectors or terminals. For example, single speaker mono radios only have light/dark green speaker wires going to terminals A and C on the white connector and the blue rear speaker connector isn't even used at all.

The black 2-terminal connector used on digital radios uses Pack-Con terminals and is usually on it's own sub harness. The orange wire usually plugs into the "BAT" tap point on the fuse box. And the brown wire usually plugs into the parking light circuit on the headlight switch.

Speaker Information

Polarity:

Speaker terminals are often (but not always) marked with + and - symbols to denote the polarity. Connecting them backwards won't do any harm but it will cause the speaker cone to move in the opposite direction. That can cause sound cancellation issues if one speaker is wired correctly and the other is wired with reverse polarity.

On speakers where the terminals are not clearly marked, a quick check can be done using a 1.5V battery. Disconnect the speaker to be tested and temporarily hook it up to the battery while watching the speaker's cone. If the cone moves out then the speaker's + terminal is the one hooked to the + side of the battery. If the cone moves in then the speaker's - terminal is hooked to the + side of the battery.

Grounding:

Most 60's and many early 70's Delco radios use grounded speaker systems. With these grounded speaker systems, the negative (-) speaker terminals are connected to the vehicle's metal body. And any negative speaker connections on the radio plug are internally connected to ground (the radio's metal case). This allows rear speakers in some car applications to only have a single wire running from the radio back to the speaker (and a short ground wire from the negative speaker terminal to the car body).

Delco radios from the mid/late 70's and newer have ungrounded speaker systems and will be damaged if any of the speaker wires are connected to ground. When in doubt, run all of the speaker wires back to the appropriate terminals on the radio.

Impedance:

Most transistorized Delco radios (as shown on this page) have the output transistor(s) biased to work with 8Ω to 10Ω speakers. I have read (but not confirmed) that the 1979 & newer ETR (electronically tuned receiver) Delco steros have amplifier circuits capable of driving 4Ω speakers.

Here is a good source for 8 - 10Ω speakers in the correct sizes to fit most older vehicles: S & M Electro-Tech Classic Car Speakers.

Stereo Separation:

Stereo channels are typically separated left and right. However, some vehicles have one stereo channel feeding the front speaker and the other channel feeding the rear speaker.

Other External Components

Fader Controls:

Most applications with rear speakers use a fader control to split and adjust the output between the front & rear speakers. These fader controls are a specially constructed rheostat that slides over the radio's tuning shaft. The fader control assembly also includes a knob (that is styled to match the application) and wires that plug into a speaker wiring sub-harness.

Example: A couple fader controls & close up of one installed on a 1963 Chevy car radio

Sometime around 1972, Delco started building radios with built-in fader controls. The built-in control eliminated the need for extra wiring and provided rear speaker output connections directly on the radio. The letter K near the end of the radio's Service Model Number designates a model with an integral fader control. I believe dealer installed rear speakers continued to use the external fader controls.

Convector Assemblies:

All radios covered on this page have the output transistor(s) mounted on a heatsink. Most are an integral part of the radio assembly. However, some applications (like early AM/FM receivers) did not have enough room inside the radio case so these components were mounted externally. These external heatsink / transistor assemblies were refered to as "convector assemblies" in the Delco radio literature.

A radio that uses one of these external convector assemblies will not function correctly without one. However, a missing convector assembly usually isn't a major problem. A functional replacement can often be constructed using parts salvaged from a similar vintage Delco AM radio.

Load Coils:

As with the convector assemblies, the load coils were typically an integral part of the radio assembly. But some applications (mostly Corvettes I beleive) had them mounted externally (often attached to the speaker).

Static / Noise Suppression

Factory radio installations included a number of additional components throughout the vehicle intended to reduce noise and interference. These typically included capacitors (aka. condensers) connected to the ignition coil, voltage regulator, and heater blower motor. Additional ground straps were also included with factory radio installations. And some applications added a grounding tang (to the cowl / upper firewall area) to insure a good ground connection to the hood.

Modifications and Add-Ons for FM and Auxillary Inputs

FM Converters:

Factory AM/FM radios for 60's and early 70's applications can be difficult to find (and often expensive). This is especially true for vehicles with the 6-¼" knob spacing. A quick and easy solution is to use the stock AM radio along with an AM/FM converter. These converters were manufactured/sold by a number of companies with Audiovox, Kraco, Realistic (Radio Shack), and RCA being some of the more common brands.

Photo of typical AM / FM Converters

Installation of one of these converters involves unplugging the antenna lead from the vehicle's AM radio and inserting it into the socket on the back of the converter. Then plug the antenna cable from the converter into the antenna socket on the AM radio. Hook up the converter's power wire (through an inline fuse) to a +12V source that is switched on/off with the ignition. Mount the converter (usually under the dash) where it's tuning knob will be within easy reach. The mounting bracket usually provides the ground but some converters have a separate ground wire or ground through the antenna cable shield.

Operation of these converters is simply a matter of tuning the vehicle's AM radio to the converter's output frequency (typically around 1400kHz) and then using the tuning knob on the converter to select an FM station. However, one disadvantage of using an FM converter is that they typically don't offer any station preset buttons. Although, that's probably not a big deal if you usually only listen to one favorite FM station.

Auxillary Inputs:

An increasingly common modification is to add an auxillary (aux input) jack to allow a portable CD player, MP3 player, or other source to be fed into the audio amplifier stage of a stock radio.

Here are some links showing how to perform this modification (use at your own risk).

Knobs and Mounting Hardware

Knob Styles:

Many different knob styles were used on these radios over the years. The outer knobs (for volume and tuning) are designed to fit onto a D-shaped shaft and are generally interchangeable among all of the Delco radios covered in this guide. The inner knobs (for tone and fader) also have D-shaped openings and will also swap among most of the radios covered in this guide. However, some designs have different depth offsets to fit certain vehicle dash bezels, limiting their interchangeability. Also, applications without a fader control typically use a decorative ring (with a round hole) in place of an inner knob behind the RH tuning knob.

Mounting Hardware:

All radios covered in this guide attach to the vehicle dash with nuts behind each of the knob locations. Most use hex nuts (that take a ⅝ socket) while others have round nuts with 2 notches in them (that take a special spanner wrench). Some applications make use of stamped steel cup-shaped mounting adapters to take up the size difference between the holes in the dash bezel and the radio shafts. All applications have some sort of brace to support the radio case so it's not just hanging by the two nuts behind the knobs. These support braces are fairly vehicle specific and might not fit directly onto radios swapped in from other applications (like the '63-'64 car vs. '64-'66 truck radios shown earlier in this guide).

Model / Service / Reference Number Identification

GM Delco radio receivers from this era originally had a paper identification tag pasted onto the case. The location and information provided on the tag varies by year. Some of the early years had the tag on the inside cover.

Most 1968 & earlier

The Model Number on these radios can be used to identify the original application. A list of model numbers & applications can be found at: WonderBarMan.com -- Delco Model Numbers and Date Codes.

Late 1968 - 1975

The Service Model Number on these radios can be decoded as follows:

More info can be found at: Chevelles.com -- Decoding Radio Tags.

1976 - Mid 1980's

The Service Model Number or Service Reference Number on these radios decodes much like previous years:

Late 1980's & Newer

Delco changed back to individual model numbers sometime after 1983. I do not have a list of these numbers.

Links to Additional GM Delco Radio Information