Hipo alternator pulley

At that point I think gold di-chromate was the finish being used.

Not sure what the MCA rules say - but I'd see if you can find some owners with original cars to compare.

The original HiPo alternator pulley on my late March 66 SJ car was (still is) black.

Believe this is current MCA language

"65-66 Alternator: Natural aluminum with semi-gloss black or zinc dichromate 13-blade fan and pulley."

HiPo alternator fans and pulleys closely followed what was happening on non-HiPo cars of the same time period. What I found was that ALMOST all 66 production alternator pulleys and fans were semi-gloss black. In 1967 production there were almost all natural (anti-corrosion finish). There was a transitional phase very late in 1966 production, possibly into very early 67 production. It is probably a case of where the vendor made the transition over night, but the alternators were arriving in batches, so some first-in black pulleys/fans might be last-out going on engines. Hence the mix where you have black, then naturals mixed with blacks, then blacks mixed with naturals, then all naturals. It drives the enthusist nuts trying to figure what is correct at a specific point in time.

Then trying to codify this in a rule book causes its own set of problems. Allowing for either over too broad a time period results real errors. For example, I have never seen a natural pulley/fan on an original 1965 car -- all were black (except for some blue ones, but that's another story).

Don't know what the rule book says, but I believe all HiPo pulleys were steel -- never aluminum.