the 81 i just took possession of has an older pioneer unit in which is currently inop.  i have the replacement ready and when the time comes check the fusing etc. the PO installed a small amp in the pass side storage bin.. dont know if it works yet. my question is , i eventually plan on updating the speakers. when aftermarkets are put in , did they need a GM wiring harness adapter? or did most people just cut and crimp?

When I changed the rear speakers in my 81, I just cut and crimped the pigtails that pioneer provided onto the stock wires. Not sure if there is a GM adapter but if you don’t plan on putting the stock speakers back in, it won’t matter.

Curious about the Pioneers... Were they a direct fit? No mods?  Model Number? Got an 82 that needs replacements in the rear. Imagine the fronts are in same shape. Thanks!