John Z is bang on as usual!
The 6,000 mile 67 Corvette has WB2C bolts and the bushings are the small diameter ones the same size as the AMK Bushings B-10243 which show the GM part number # 381957.
I also looked at his 70 Ram Air 4 Trans Am, 20,000 mile car, TOTALY original, it also has small diameter bushings and the WB bolts have WB only.
I have pulled off 1 of my original WB bolts, and I was surprised to find the bolt shank diameter is .342 ( 11/32") NOT 3/8" as I posted earlier. They do have 5/16 Thread on the top. The HBC bolts are the same diameter, as well as another set I have. I allways thought they were 3/8" but they are not.
The AMK small diameter bushings apprear to be correct at this time, and the hole size is smaller than 3/8 to correspond with original bolts. I also checked some Generic aftermarket link kits and they are 3/8" bolts with the larger diameter type bushings.
Chick and Jeff - I Hope this helps.