Under dash wiring harness

[Gromit]

Another way to check might be to look on americanautowire.com and look for the "Factory Fit" product line (not Classic Update) for the vehicle you have in mind. If you look at their product / price list on pdf for that Factory Fit line you can see all the different options and harnesses for various vehicles. I have found them to be accurate for what I've used from them - and when I have asked questions their staff seems competent. My 1970 A/C truck (C10) had a separate A/C harness. The heater blower is still on the dash harness.