Are there physical differences between Gen 6 502 valve covers and the ones used on 500 EFI or 525 engines or is it just the color? Asking because I used GM performance with my 502 with roller rockers and had to use two gaskets to make them clear. Would like to avoid that in future, but don't want to pay some big money for the Merc racing ones just for the paint.

It's not the valve covers that are the problem, it is the polylock nuts on the rocker studs. The OEM poly locks (on 525EFI's at least) are shorter than those that come with other rockers so if you replaced rockers but didn't reuse the poly-locks, the valve covers do not clear.

some of the tabs need to be cut out from the underside as well to clear, and yes short poly locks needed

Thank You

So the valve covers are the same other than paint?

yes, I'll have two sets of the stock 525 locks available, Im running girdles and tall locks so don't need them

Edit: the mercury racing 525 have the embossed logo on it, so its just not paint

I wish that I understood that shorter poly locks were an option before I spent $400 on valve covers that I didn't even really want.;p