Lemme dig up my book and I will scan a few pages for ya.

I have a 1976 Cutlass Supreme 4-door sedan with the 350. I have the
schematic in the Haynes Manual. I also have a 1974 GM factory manual
for the Chevrolet line.

If your question is about the tail lights, then I'm going to step out
of line and guess that you have a ground problem.

The tail light sockets are plastic. They mount in a glass fiber panel
on each corner of the car. Ground is not accomplished through the
carbody. Instead, there is a metal finger on each socket for ground.
This finger is compressed when the socket is twisted into the bayonet
mount in the glass fiber panel. When the finger is compressed, it makes
contact with another metal part on the tail light socket, providing the
ground for the circuit. If that contact is not made, the lights will
flash erratically.

I fixed the problem by soldering the finger to the contact several
years. Since then, all my tail lights have worked flawlessly.