Steel 1/2" dia round stock, 3/8" tall, drill with a #9 clearance drill for a #10-32 screw to attach them. I used a Whitney Jr. hole punch to punch the holes in the tempered steel clips aquired from one of the vendors.
This was for the 3600 hub caps, if you have a 3100 they may be different.
DG

Last edited by Denny Graham; 02/26/2011 2:59 PM.

Denny G
Sandwich, IL