GM part number

I found a couple of NOS bumper guards the other day, still in the box, and I'm not sure what they're for. Can anyone help, or tell me where to look?

The box reads:
Model 4503 AX
Group No. 7.828
Part No. 3658726

I will probably want to sell them, but I don't know what they're worth. Can anyone help?

You can Email here and request what they are for......Customerservice@GmPartsDirect.com Maybe they can help

Try your favorite GM parts guy....he can run the number and see what it fits....for any GM car. You dont have a "favorite" parts guy? You're not buying enough parts!!