I have no specific knowledge but would assume if it was the same part, it would have the same part number.
I wouldn't think there are a lot of interchanchable parts. If you want to test your theory, maybe look up the numbers for the fuel cap, and the expensive rod ends at the top of the vertical struts on the Full Floater suspension.
(High chance one or both of these parts are common, even though the tanks themselves are different....so... Maybe the cap...)
From memory I bought a new cap, with all the seals etc. Again from memory - reasonably priced.