I have two almost identical trucks that I am working with here. '85 F250 ex cab, long box, 4x4, 460, manual trans that is in good shape. No AC. The donor is the exact same truck, just is an '86 with working AC.

My question is - will the heater box/plenum/etc (the piece under the hood) fit my non-AC truck without modifying the firewall? IE, is it direct, bolt in replacement? I know I am dealing with changing the whole dash, wiring harness, etc. That's fine, no prob.

Just trying to get my ducks in a row before taking things apart. I tried searching around but couldn't find an answer specific to my question.

 

No. I read just a couple of days ago where a guy said, IIRC, that he'd done it and would never do it again. It took a lot of modification of the firewall. But, don't take my word for it. Do a search on this forum re "AC" and "firewall" and you should find someone saying he has a whole unit for sale and someone else saying it ain't easy.

 

Think I found the thread about it not being easy, sounds like it's just some cutting and swapping. That answers my question, cutting doesn't bother me, I did a V8 and solid axle swap in my Ranger a couple years ago. This should be a piece of cake. Thanks!

 

As long as you know what you are getting into then go for it. And, let us know now it goes as others might like to do it.

 

Will do, might take a few pics and put a tech thread together if I can remember.

 

It's bound to be easier than installing AC in a non-AC 77 F-150. The AC system on those is huge. One item that may give you a real problem is the inside distribution box, I pretty sure you will end up removing the dash to change it.