I had thought about tearing the factory radio apart, I would need only the main board, the radio chassis, CD unit and tape deck could be removed, then tuck it up under the dash, and run the wires. In my case, I would need only the variable voltage in (grey) and the dimming trigger (yellow) and the dimming-signal-to-HVAC, the white/purple, and the ground. Maybe the constand hot, but I'm not sure about that yet. Keeping the radio totally intact would be nice, however, since that radio will go back into the car at some point, so I kinda like your idea better. So I should get my hands on the wiring pigtail from a wrecked car.
But I agree, there really should be a better way, and Crutchfield was stumped. Heck, they had a neat infrared repeater so I could continue to use my steering wheel buttons with my new stereo, but no one could help with my HVAC dimmer. Mike.
1993 Bonneville SE, frame off resto in progress, will be stock except painted black & chrome t-stars, estimated finish date - spring 2009.
Cars in my "fleet": the bonny project, the bonny parts car, 1999 Olds eighty-eight LS anniversary, 2004 chrys T & C.
Husband, father of two daughters, deer hunter and lover of most things GM, (although I do like my Chrysler minivan) - but nothing comes before my girls..
I'd much rather go home after work and be with my family than do anything else..