My 69 was originally a small block car. So when i installed the new big block core and big block heater box I noticed two holes where the small block heater core tubes were.

I need some ideas on how to fix, weld patch ........

I snapped some plastic plugs in my a/c small blocks when I installed vintage air. I have pierced a hole in one to run wires to the inside. I bought these caps or plugs at an Ace Hardware store !

http://i263.photobucket.com/albums/ii152/tjs69_photos/Heater%20core%20plugs%20and%20add%20on%20fuses/000_0431.jpg

I know they are not in the same spot but, you should get the idea.

thanks, thats a great idea.

Factory used a thick piece of closed cell foam, glued to the inside (interior side) of firewall to cover the L6/small block firewall holes.

I'll dig around to see if I can find a pic or two.

http://www.camaros.net/forums/showthread.php?t=103810&highlight=heater+core+foam+block

OK, so you can put a big block heater core and box in a small block car?

thanks eric

Just was i was looking for.

OK, so you can put a big block heater core and box in a small block car?

Yes.