Need some rear shock install help

[atm70chevy]

I have installed rear shock relocators from Classic Parts with new lower studs on my truck and ordered some Belltech Nitro Drop 2 shocks. The studs are too big and will not fit into the bushing on the shock. I hve verified with Belltech that I have the correct shock and also called Classic Parts. The new lower studs that they sell are the same dimensions as the facotry stud. Has anybody ran into this problem before or have any ideas what to do to fix it? The guy from Belltech said they may could send me some bigger bushings for them but I don't understand if all the part numbers are correct why they do not fit.....