[KangKwad]

The center caps are small rubber caps that hook on to a 4 tab metal washer behind the hub nut. If you are expecting it to be some kind of fancy plastic color matching hub cap you are going to be in for a disappointment. I dont think it matters of the wheels were metal or aluminum. I dont think the Vinson was ever available with steel wheels anyways.

As a matter of fact i think my 2021 King Quad with steel wheels uses the same exact rubber caps my 2007 Vinson had.

 

[KangKwad]

I see the four tabs washer on the diagram but I don’t have them on my machine.
I do have 1 inch spacers though and they will look pretty strange if the center caps are not fixed on the wheels but on the bottom of the hubs…

The previous owners probably removed them to run the wheel spacers. Personally i would remove the wheel spacers to get the proper scrub radius back. What size tires are on it?