1965 Brooks Robinson Does not have T.C.G. Printed In Canada on the back side. There is no variation on this. They all come this way

1975 O-Pee-Chee, not very many people know about this but the light blue/Green cards, many, but not all are about 1/16 inch short. This is the only color scheme that comes short. In this picture, you can clearly see the light blue shorter to the Dark green/light green card.

The first year with size issues was 1968 O-Pee-Chee. I will update this with the numbers once I am able to dig them up.

1971 O-Pee-Chee Baseball has 2 cards with Red Letter and Yellow Letter Variations.

Card #27 Pirates Rookie Stars and Card #144 Jackie Hernandez. In both cases, the Red version is much more difficult to find.

There is also checklist variation with the location of the number on checklist #123 and "Printed in Canada"

1981 OPC Gray Back and Cream Backs

Pictured here are 1981 O-Pee-Chee Rickey Henderson in both Gray back and Cream. It is very easy to tell.

Gray backs to carry a slight premium 

Here is another picture...

1990 O-Pee-Chee Vending Boxes/cases. Little known on the print run on these but very hard to find. The biggest issue is that the cases don't say Baseball on them. OPC was known for printing a ton of the hockey so there is no way to know if it's baseball unless the case is opened. I was luckey enough to find a couple cases in Montreal