new catalytic converter, Need bolt size 2 replace bolts to mount to engine.

Consult your local GM dealer to acquire the proper bolt.

I called the dealer. They said there are no specs on the bolt size so they just drill it out sand put a bolt with a washer and lock it on it. It take 3 bolts and a gasket. Made three trips to autozone before found the right "universal" kit. But thank goodness it's fixed now. Thank you for your help!