Nathan - According to the Chevy Master Parts Catalog descriptions, the original rubber core support pads (GM# 3684763) dimensions are 2-1/4" x 1-1/4" but no specified thickness that I could find. Ditto for descriptions from the various regular vendors we tend to use. IIRC correctly they were about 1/4" thick. Jim Carter sells the pads as
ME195 for radiator supports that use the two mount system. The FAM shows 2 mount supports used for 3100 - 3600 models and a single center mount radiator support for 3800 - 6000 model trucks, which use a different pad and bolt setup.
I tried to look up the GM part numbers listed in Gord's reference and could not find matches to any of the "shim" numbers except for GM# 366981. That is listed as an AD series truck "cab" body mount shim. Nothing showing it listed for the radiator support.
As far as shimming goes (to help get front sheet metal alignment), the only vendor I found that seems to offer radiator support shims for the AD series trucks is
Chev's of the 40's. They don't mention pad or shim dimensions, nor do they indicate how many "shims" are included in their kit???
Hope this helps some.
