[jonzcustomshop]

I went through quite a rodeo yesterday putting a good heater in my wifes 63.
found out a bunch of stuff about interchange.

I will list off what I found out, and try to get some pics up soon.

please add info if you have it.
If I have any of this wrong, let me know and I will edit it in.

As far as I know there are 4 heater options 60-66 chev and gmc.
1) no heater: firewall delete plates- 60-66 (upper delete plate is the same all years, lower is 60-61, and then 62-66)
2) cheap heater: "recirculating", core and fan inside cab- 60-63
3) cheap heater: "thrift-air", same as deluxe, smaller core but only 1 knob for fan and air.-64-66
4) deluxe heater: "deluxe", core and fan in engine compartment.-60-66

All I can talk about now is the deluxe models, as I don't have any cheaper ones.
60-63 all have the same box on the firewall, it is shorter and more rectangular than the 64-66 which looks like gm modified so that a paper element air cleaner would fit with the V8. this one is longer (towards the front) and has an angle notch on the engine side.
my 60 fan had a longer motor and an electrical connection that looked similar to a thumb tack.
it also had a lower bracket that bolted through the fire wall.
although different it did fit on the 63-66 boxes.
the 63-66 fans all looked the same, with a regular plug in connection.
all the ones I had have a metal squirrel cage, except 1 which was plastic. (66, or replacement?)

the holes through the fire wall look to be the same 60-66, however my 60, and my 63 both had provisions for the heater fan bracket.

I was able to install a 64-66 box on the firewall on my 63, but I had to drill a hole 1 inch closer the fender to mount it (64-66 boxes have a 1 inch wider mount than a 60-63.)
I also had to drill a different hole for the "heat" control cable, those also come through the firewall in a different spot.