WTG - Want to Get

Don't know where I lost it, but it's gone.  Just the little plastic strip
left that held it when it was off.  You know what I'm looking for.  Just
foward of the propane tank on the underside of the van is the pipe where the
sink drain exits.  There is (or is supposed to be) a screw on plastic cap,
attached with a little plastic keeper (that's still there dangling).

Mine obviously ran off down the road somewhere.  I'd like a new one of some
sort.  I see that the BD offers the entire drain pipe with the cap, I think.
I just need a cap of some sort.

Has anyone found a substitute that would fit??

Thanks,

John Graham
88 Westy
Charlotte, NC