Frank50,
In addition to your comments, "The 216 style cover with 2 studs coming thru the top has stiffening ribs formed in the top and sides of the cover to add strength. The crew type do not have those same ribs." : I think that the the 2-stud USA valve cover does not have a lip around the bottom. A lip would be needed for the 4 side-screws on the "double-duty Canadian valve cover?
It would be very interesting to see that Canadian valve cover - I do not doubt Lindsey's statement - GM/Chevrolet/GMC Canada was somewhat independent/different from GM/Chevrolet USA in its use of Chevrolet & GMC engines.
