Bought 2 front rotors (w/o hubs) at Autozone for my 86 10-bolt. Rather than reusing the old studs I figured I would just get new ones. They look them up in their computer and bring out 1/2"-20 thread studs. Well, I have 7/16"-20 studs and lugs on there now. I tell them that the rotors and studs have never been changed and that 7/16" is stock. They tell me that the 1/2" is all they list for my truck. I reluctantly take the 1/2" studs and ended up buying 12 new 1/2" lug nuts to go with them. So I get home and pull one of the new studs through the new rotor using the washer and impact gun method as I have done many times in the past. The stud gets halfway in and the rotor cracks. So I take everything back to Autozne and tell them that there is no way these are the correct studs. They give me another rotor and I tell them to keep the studs, I'll look elsewhere. I go to 4-5 different parts stores and they all list 1/2"-20 studs and none of them fit into the rotor. I also ask them to pull out a rotor so I can compare it to the one I got at Autozone. Sure enough, they all match. So I go to a GM dealer. Take in the rotor and tell them that I need studs. They look up the studs and bring them out and although they are 7/16"-20 they still look like the seat is too big to fit in the rotor. So now I think, "This has to be the wrong rotor." But, of course, the dealer doesn't have a rotor I can compare mine to. I can't believe I'm having so much trouble finding the right studs. Anybody else ever have this problem?