Yes, I meant zinc plated, not galvanized.
John, yours looks to be more heavily stamped, giving and almost embossed look to the text and the circle around the AC and RC-15 being slightly depressed below the surface of the surrounding metal, which is exactly how I remember them from those days.
While we're on the subject, below is a couple of before and after cleaning pics of my '86 VL Commodore cap [GMH built car].
They weren't using AC caps by then, they were all built by another local company - CPC.
I cleaned it with CLR bathroom tile cleaner which is a weak organic acid [I think], spraying a bit on, then gentle scrubbing with a soft toothbrush then rinse off.
It only took about 20 secs for each side. I moved as quickly as I could so the acid had little to no chance of attacking the zinc.
I then phoned CPC to see if they could rebuild it for me, as all the rubber bits were shot.
To my shock and surprise, instead of the expected loud laughing ["You want us to do what!!...
] I was put through to a guy who said "Sure, no probs, send it over and I'll do it for you"
After I got up off the floor, I asked him how much. He said he'd do it for free!!
The last couple of pics are how it looked after coming back from CPC.