Prior to 1968, Delco Radio Division of GMC just used part numbers for identification and they were assigned mostly sequentially. Mist are of the form 98xxxxx or 72xxxxx though often the using model line (which included Studebaker and Dodge) would assign their own. For example '61-'63 GMC radios all are of the form 22xxxxx. These just need to be known.
However for the 1968 model year, Delco Radio adopted a standardised coding for GM-Model-Line radios which make it very simple to tentify exactly what a radio is by features, make, and model year. A sample of this "Service Model Number"is:
How ? Easy.
The first digit is the model year of the radio - 8 = 1968, 0 = 1970
The second digit is the car line:
1 = Chevrolet 2 = Pontiac 3 = Oldsmobile 4 = Buick 5 = Cadillac 6 = GMC
The third element is a letter which corresponds to the fisher body style the radio goes in:
A - Midsized Tempest B - Fullsized Bonneville C - More than full sized Cadillac Fleetwood. D - Rear control Cadillac 75 F - Pony car Firebird G - A special Grand Prix H - Subcompact Sunbird X - Compact Nova
The next two letters indicate the type of radio:
PB - AM FP - AM/FM mono FM - AM/FM Stereo MP - FM Multiplex adapter (second part of a two-piece radio) TZ - Stereo Tape Player (8-track) RV - Reverberation Amplifier FW - AM/FM/Weather band MW - AM/FM stereo/Weather band
In 1970, integrated AM and AM/FM stereo/8 tracks becane available which added a third letter - T or "PBT" or "FMT" (yes Virginia, in 1970 there where a lot of AM - 8 track combos sold, FM stations were still a rarity in many parts of the country).
Finally there may be a digit (1, 2) on the end which indicates a running change or revision number.About the ultimate was reached in the late 1970s with the model xxBFTC1 - An AM/FM stereo/8 track/CB unit in three pieces - the radio unit which went in the normal dash position, a CB unit which contained the transceiver electronics, and a control head/microphone. About as much as was ever put into a Delco radio.