Full Wheel Covers ???

[TBONE1964]

I am interested in some information on the full wheel covers that Chevy/GMC used on the 71/72 year trucks. I know that the same basic wheel cover continued into the 73 + year trucks but not sure about the changes. I recently bought some used covers and found that one of the covers has a plastic center cap and the other 3 have a pot metal type center cap. From 20 feet, they all look the same.

As far as the cover itself the one with the plastic center cap also has a hole behind it and I thing that was made for a 4 wheel drive but they used them for rear covers as well.

Does anyone have any knowledge of these wheel covers? I would love to learn more about what the differences are and how to make sure I get what I need.