but a reduced diameter shank is nothing to worry about provided the diameter is the same as the thread's minor diameter. ARP has offered domestic V8 head stud kits for years that feature undercut short studs so their overall stretch is closer to the long, non-undercut, studs... this is done to help with when the headgasket inevitably compresses a bit, the short studs won't lose any more preload than the long studs.