Dan,
I wish I could help but it's going to be several days before I can go to the shop. I remember that my 60 has the same connection s that yours has coming from the back up light switch and those two wires go up the firewall and from there I'm not sure where they go through the firewall.
I doubt the Pontiac being the same as the Chevrolet, the 60 and 61 Pontiac's use a fuse box that is wired into the harness , the Chevrolet wires plug into the fuse box. That's why the Pontiac harness is so expensive.
I wish I could help but it's going to be several days before I can go to the shop. I remember that my 60 has the same connection s that yours has coming from the back up light switch and those two wires go up the firewall and from there I'm not sure where they go through the firewall.
I doubt the Pontiac being the same as the Chevrolet, the 60 and 61 Pontiac's use a fuse box that is wired into the harness , the Chevrolet wires plug into the fuse box. That's why the Pontiac harness is so expensive.