How close are the date codes of # matching engine parts normally? I have a 68 400 HO 4 Spd, with the correct #’s matching block and 16 heads with date codes of J137 and J167, I don’t have the 9790140 intake though, would that be within a few days also? I found one with a H227 code, but would that be to big of date gap to be “correct�
