Im calling BS to this " -1 is better than -8 (or even 15!)" hogwash. Id like to propose a theory that the suffix behind the 2780930-340-x is nothing more than a 4 based (?) casting cell number or casting position in the foundry, Not a core change or revision number. The sand cores were all identical, held to a precision that a sand casting could hold. They were not different from a -1 to a potential -16. If a casting core changed, so did its block casting number. Calling all 340 owners: post your block casting number, and 340-x suffix and date of manufacture. I bet we'll eventually get different suffix numbers on the same date of manufacturing and even low numbers cast days after high numbers *. Ill start with @5150DodgeBro pristine example of a very early 340 casting date, and then a few more from our own FABO site. 2780930-340-4 produced 6/22/67 2780930-340-3 produced 6/23/67 -----* BUSTED!!!!! ----- 2780930-340-3 produced 5/07/70 2780930-340-1 produced 1-18-71 2780930-340-7 produced 9/25/72 Lets see 'em!