The heaters GM Canada used are nothing like the American ones. If it says GM on the front then it would have been dealer installed. Does it look like this?:

http://www.ironchief.com/gallery/view_photo.php?set_albumName=album03&id=DCP_2073

The core may be plugged. Hook a garden hose up to it for testing. Good luck.

Curt B.

1952 1300 Canadian 1/2 ton restomod
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