You want stainless steel lug nut covers. Don't let the Freightliner ealer tell you this is all we have, a big bin of cheap Chinese plated stuff that fits loose and will rust the second time it rains.
They have the number in their catalog. They cost more.
Also don't buy the cheapie hubcover.
You are talking about dual rear wheels with aluminum wheels?
The big hub cover cost a pretty penny so don't settle for chap junk that will rust. OEM is stainless.
The Freightliner center cap for the hub cover is also not cheap.
That's the reason they stole yours.