I am just trying to determine if my wheels on my 76 280z are stock or not. I have attached photo's below.

Also, what are they called?

There are no stock alloys prior to the "iron cross" wheels that come out in '78. Just steelies and three kinds of hub caps depending on year. Any alloys were dealer supplied. Might of come from the show room with them, but not from Japan! At least in North America. There are several excellent wheel experts who will likely chime in any second about the origins yours, but they are not "stock".

Those are American Racing "Vectors". Widely known as "Dukes of Hazzard" wheels. I have a set for my race car.

OK, thanks. Any idea where I might get a couple of the center caps? I am thinking about doing some painting on the wheels but not sure. Long term plan is to get new rims and tires in about 1 year.

No idea, but I'd try ebay. They sold loads of those wheels in every size and bolt pattern. Measure the center bore and see if you can find a match.

Check out Summit Racing. I just ordered some steel chrome center caps for my American Racing "Spectres." Only paid about $30 for all four.