Originally posted by MalibuChevelle
On blocks with a stronger nickle tin combo there is a third # usually .015 and as for the mexican block they have an M in the casting # and no the M is crap metal. Look for 2 bolts w/ 3 sets of .0xx #'s not just .010 .020 those are standard.
Hum, thats pretty interesting, I've always heard about the high nickel blocks but nobody was ever able to explain it (or didn't want to give up the secret) will this hold true for the 400 blocks ???