no one makes screw rocker studs for AMC heads so the chevy ones work well. the 7/16th part is .015 longer than the stock amc studs so ya can run guild plates without more head work. don’t forget the lock tight and tourqu them to speck and ya good to go. im running 1.6 full roller rockers and a stiff springs for over 6500 rpm and i wil be running a guerdle. …. just so i sleep better at night.