You can create a signature block with your RV and tow vehicle information (see mine below). That way you won't have to repeat that information whenever you post or ask a question. You can create a signature by going to:
Forum Actions (on menu bar) -> Edit Profile -> Edit Signature (under My Settings on the left)
FWIW those are pretty much standard across trailer wheels so any generic one for your wheel size (opening) would do. It'll probably save some cash over obtaining one from a GD dealer. https://www.trailer-wheels.com/Center-Caps_c_278.html
I lost one of the plastic snap in caps on my last trip. According to GD parts lookup, I have the 140002 center cap - 4.88. I see etrailer.com has a replacement that seems to be an exact match because the code on the back "60C" matches what I have and the dimensions look right. However, they charge $10 per cap! After shipping, that's quite an expensive piece of plastic.
I do see I could order a full cap + plug from trailer-wheels.com for $12, but I really don't need a replacement metal part also. I ordered something on amazon that was very close to the dimensions I measured with my calipers (4 caps for $17), but they didn't end up fitting. Am I nuts for thinking getting the right part ordered online should not be this hard or expensive?