I got two C5ZF-144031-A in front of me, both from Oct build San Jose 66 Mustangs (San Jose using up old inventory). The markings are faint; the insulators gone (two used for C5 cables); the clamps were reused; one says Canada, the other does not; both say SX and FOMOCO. All four terminals appear to have been dipped in hot solder which covered any terminal markings. (I have a 66 reproduction cable that has a terminal marking.) Three of the four terminals are round, the fourth has a small tab, 1/8 x 1/64 inch.
What I've found is that the repro clamps and insulators are the giveaway, especially the insulators. It's a "subjective" observation, you can either see the differences or you can't.
Jim