HEY THAS GREAT, I FINALLY GOT TO MEASURE THE HD BOLTS , I COULD NOT FIND MY MIKE THAT NOT WHERE IT WAS SUPPOSSED TO BE , BUT ANYWAY , I MEASURED A USED BOLT AND A NEW ONE AND THE NEW ONE WAS 7/10 THOUSANDS SHORTER THAN THE USED ONE , HAVE NO IDEA HOW LONG THE USED ONE HAD BEEN USED , I JUST TOOK IT OUT OF A CYL HEAD AND MEASURED IT , EVIDENTLY NOT A LOT OF STREATCH . JERRY