Tab - I added a spacer about 1/8" thick under the clips. The wheels are from a 91 gm 3/4 ton and have a deeper well.
First the hubcap.
http://www.myoldtruck.com/gallery/files/2/3/8/Hubcap.jpg
A close-up of the clip
http://www.myoldtruck.com/gallery/files/2/3/8/Clip1.jpg
and a close-up of the lug for the later model hubcap
http://www.myoldtruck.com/gallery/files/2/3/8/ExternalMount.jpg

Fred
52 3600
69 C-10