AM/FM Stereo Adapter
Short answer: Yes — the factory AM/FM radio came with a “shorting plug” in an auxiliary socket; the dealer removed it when installing the FM multiplex (stereo) adapter. The plug has a vacuum-tube-style pin layout carrying the volume, balance, and tone controls.
When the multiplex adapter plugs into that socket, it disables those functions in the radio and moves them to the adapter, adding the second stereo channel across the 4-speaker system. This was the dealer-installed setup for 1967–68 Firebirds (other models could get a similar system as factory equipment). The pin count in that socket also helps a radio expert confirm a unit is a correct Pontiac radio.
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Content last modified: June 13, 2026 at 10:06 am
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