I have a 69 Chevelle that origionaly had A/C, somebody removed the entire A/C and heater unit on both sides of the firewall. Before I installed my new big block (502) motor in the car I completely filled the hole in the firewall with a piece of welded in sheet metal. Now I have no opening. I want to put in a non A/C heater box on both sides. Does anybody have sizes or pictures of the opening? Do I need to get a heater box from a big block doner car or are they all the same?

They are all the same from 68-72. Just out of curiosity, why didn't you just put the A/C box back on the inside of the car and put up an A/C delete box on the outside of the firewall. It would have been easier.

Yea that would have been easier but I was not the one who removed all the parts, so I was starting from scratch. Not to mention this was 10 years ago now

here's a picture of my 68 non A/C firewall
http://www.chevelles.com/showroom/1968SS/firewall2.jpg

Oops, forgot the blower motor hole located under the right fender
http://www.chevelles.com/showroom/1968SS/firewall1.jpg

Wow! I'm very suprised the non A/C hole is that big. I would have bet money that an A/C hole would be the bigger of the two! Thanks

Wow! I'm very suprised the non A/C hole is that big. I would have bet money that an A/C hole would be the bigger of the two! Thanks

The A/C hole IS bigger

What do you meen the A/C hole is bigger? The hole in my firewall was smaller than the one in the above thread picture!

Well I know on the 70 we removed the A/C and put back a heater only plenum and I had to patch the "left over" hole that the plenum didn't cover, as I recall it was about 4" or so.

OK now i'm really confused! Can someone please tell me or show me the difference between an A/C firewall hole and a non A/C hole?