Figure 15-72 in the '69 Pontiac service manual shows the setup for the FM Stereo Radio-Firebird. This includes the amp connection. Sorry I can't scan and post it right now, I sold my computer and the temp doesn't have all the toys.
Figure 15-68 shows the stereo wiring in detail. However, they don't have a breakout of the amp pinouts. The amplifier and receiver are to be serviced as a "matched set".
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
