I build radio wiring harness' and other small wiring harness'. 64-72 Buick radio harness with radio plug 24.50, SORRY NO 65 Buick full sized cars are offered, I have no plugs for these cars. (What a weird plug). Rear speaker wiring harness with proper plugs (Blue 18 gauge wire and brass connectors) 16.6 feet long. 12.25 plus 3.00 shipping. For dual rear speakers add 6.00. Urbanxx
Have you considered the 8 track harness? I had to get one made a few years ago.........mucho dollars.
The eight track harness' are easy to build if you have the plugs (I have sold all mine) in other words they are easy to rebuild if I have the old one to go by.