General RV is where I get mine, In my case the Wixom MI store but if you send your specs, and a photo to the Customer Assistance folks at most of the major RV suppliers OTHER than camping world.. Odds are they have a box of 'em.
IF sending photo. Take at least two of the nuts, put one Cap up and one lying on it's side, threads exposed, next to a ruler or mM stick (metric ruler) and take picture including all 3
If shopping bricks and mortar.... Take one with you to match.
Joke; (Luan comic last Sunday) New store built just 2 years ago going out of business due to on-line shopping making Brick and Mortar stores fail... "What did they sell" Bricks and mortar.