Thought I would share my research trying to find decorative wheel parts. We have a 2008 Damon Astoria 3776 that we have been repairing and maintaining. There were some lug caps and hubcaps missing when we bought it and I like keeping my stuff stock. Begin the search for older parts!
Freightliner couldn't find anything in their system and recommended aftermarket. The aftermarket shop had some chromed plastic they would sell me for around $250. I tried calling Thor and finally got the part number SS-28487RV for the whole set. Thor wanted $1,115 for the set and couldn't sell anything individually.
Doing some searches online, I found Kaperii.com
which listed the set on their site. I called them and they could sell me individual parts to replace some missing items on my motorhome! Yay! 4 hubcaps, 6 jamb nuts, and 6 jamb nut covers later the total was less than $50. The entire set was less than $400 if you want to go that route. Here's some pics of what they look like on our motorhome.