AC box interchangeability 1985 to 93?

[artieb]

Hi, I may be buying a 1985 Gas truck for the cab that does not have AC. Anything major other than swapping the heater box out and the heater / AC box in? I know older GM was a pain on account the cowl. Thanks, Artie

[dazedandconfused]

The boxes are the same diameter atleast my 83s was the same as my 93. Only thing I had to do was cut the rectangular slot for the little heater looking thing.

[TRENDZ]

I swapped an 85 gasser "heat only" cab to my 91 a/c truck. the heater box was a direct swap, no cutting or welding. The firewall on the drivers side had a few different holes for wires etc... The biggest problem I ran into was the floor pan. The 85 truck was an auto trans. The truck it went onto had a 518 auto. The floor had to be "gently reshaped" with a large hammer. The o/d section of the trans hit the floor in a big way.