If you dont get an answer soon, i would just go to my local hardware/home improvement store and buy a thread gauge. Once you get home, take out one of the bolts and measure it with your new, handy-dandy gauge. BOOM, now you know what thread they are.
A forum community dedicated to Chevrolet Silverado and GMC Sierra pickup owners and enthusiasts. Come join the discussion about performance, modifications, classifieds, troubleshooting, maintenance, and more!