Can anybody help I.D. this hub cap?

[John Brown]

Here's a hub cap I bought off of e-bay. It looks just like a copo dog dish cap, but there is no Chevy bowtie in the center. Part number is 3993596 and the cap is nos.





The label on the box says ~GMC Truck and Coach Division, Made in USA~, but the inside of the cap is rubber stamped with the part number and MADE in CAN. I'd like to know if anyone can I.D. the cap by the part number, not just by the picture. I've had people guess GMC Sprint (GMC version of El Camino), other people are saying it's for a Canadian Nova (Acadian) or Canadian Chevelle (Beaumont). Might be any of the three, since the cap came from a Chevrolet / Cadillac dealership in Montana, just a couple hundred miles from the border with Canada. I tried my local Chevy parts guy, but all his contacts came up empty. Can any body help? Thanks.