Lonnie,
The panel-body rear-fender bolts and washers are completely different from the pickup's. They are not typical fender washers and the bolts are indented hex head without flange.
If Snubby does not post a few photos, I'll take one off my Suburban and post a few photos.
The bolts are available (even stainless from Totally Stainless); however, I have never seen the heavy/thick cupped serrated/starred washers for sale.