When I bought mine, the PO had just thrown a whole bunch of silicone over the cracks of my Thetford inlet. When I was doing some plumbing work around the water tank/pump area, I noticed that the inlet pipe was all cracked. I was looking all over for a Thetford replacement.
Ultimately, I ended up purchasing a PVC water fill (w/ locking cover) from Mark's RV and replaced my gray, rotten plastic one. Now, since I've got an Argosy, it was easy to simply spray paint mine ivory after making the install.
George M. Sutton (Oregon RV Dealer | George M Sutton RV | Oregon RV Sales | Oregon RV Service | Oregon RV Parts
) found an Airstream-made potable water inlet that is Aluminum (or at least it was gray and shiny and looked metallic). It was only $18. If you give them a call, I'm sure they'll be able to get you one. They gave me a part number starting with 6, but I'm not at home right now. Sorry.
So...you bought a vintage trailer, did you, honey? Good deal, was it? Oh, just a couple of repairs, huh?
Drat, now our little Argy is starting to grow on me. I guess you were...were...were...right, honey.