I have been researching head bolt replacements for hours and made no progress. I have a 48 P-15 L type motor that I am replacing the head gasket on as soon as the machine shop is finished with it. The old bolts are just that. Old and pitted as well as mismatched. I have purchased and returned two sets of bolts claiming to be correct and still no success. I don't see any one else having this problem. What am I missing. The bolts are 7/16-14 with a body length of 1.6875" + a thread length of 1.125 =2.8125. The head thickness is 1.9062 . All told installed the threads are. 2187" longer than what is secured into the block. I can't find any vendors. I can't believe I am the only one to have this problem. Also, American made Grade 8, hex flange is preferred. I really need a hand with this quandary. Please help.