The Cat dealers from time to time put out a flier catalogue called ONE SAFE SOURCE. It gives all the dimensions of all the current Cat part number bolts, including the grip length & head height. I keep a copy handy in the shop for the opposite reason: When a hardware store bolt fails I can usually find a high quality replacment of the same size at Cat. True, it's not the only source of good grade 8 bolts, but it's the handy one around here.