Yeah, and either way, you are still doing it wrong because Chevy put them in cold under high pressure. I am really sold on doing it yourself however you decide. Bolts are not the answer. The rivet expands and fills all of the hole during its cooling and makes for the tightest bond I have ever seen.
Hardest part of this is the bucking. Once you have it in the hole, having something SOLID to back it up for the final riveting stage. I didn't have Bubba so 1/2" steel and very large, very heavy C-Clamps did the trick.
