I can't find any identifying markings on this fiberglass tub/shower which was bought and installed in 1979, but there are some numbers stamped upside down in one of the upper corners. I think they read "AG609 38277". I'd also like your recommendation for a tub stopper. It looks like the diameter should be 1-3/4". I know the 2" Danco #88599 won't fit, and I'm not a fan of plastic posts.