Here's some information on what wheel(s) I'm looking for.
Over the years GM used at least two different styles of 15x6, 5-lug, 4-nub wheels on their trucks. The main difference being the design of the center portion. If you look at where the center of the wheel comes in contact with the barrel you can see that one wheel sits below the edge of the barrel and the other sits slightly above. Also, the face of the center of the wheel is concaved (curves inward) on one and the other is covexed (curves outward).
My four wheels happen to curve outward.
Here are a couple pics that show the different styles of wheels. The first one has a face that curves out like mine and the second pic shows a wheel with a face that curves inward.
