RV Parts stores or Dealerships, Camping World or try a good old fashioned "Mom and Pop Hardware Stores" or chains like ACE, TruValue...and some of the larger online RV parts suppliers such as Dyers, RVPartsStore.com, RVWholesalers.com, etc.
Near you in Maryland....beckleysrvs.com. Good luck.
My posts shouldn't be taken for factual data, and are purely fictional, for entertainment purposes, should not be constituted as related to scientific, technical, engineering, legal, religious, spiritual, or practical advice. After all it's FREE! Amen. :W