I have a 67 GTO convertible that I am working on and am in need of an engine. The car came with a WS block but the car was made on Oct 31 I think 66. I would not know where to start as far a finding the preper WS block! What date code would I be looking for. I have seen M codes on some 670 heads, but I assume that they are for Dec. What code is for Oct of the year before? The PHS documentation I have says the car was made 10/31/6 so I am assuming that this is correct. The car was number 760 off the line. Any help would be greatly appreciated!