You were right Colbyt...I'm back.

Thanks everyone with the suggestions for changing of valves. It was
actually fairly simple, the new valve fit perfectly with the existing pipe
inlets with the inlets being threaded couplers. No leaks first time around!

Anyhow, while finishing up the taping of the Wonderboard around the
bath/shower walls, I found rotten particle board around the base of the tub.
The sub-floor is in good shape but, of course, I am having to replace the
bad portions of particle board. Is there anything wrong with me replacing
the bad particle board with 1/2' Wonderboard? I'm also going to tile the
floor so I'm going to place on top of everything 1/4' Wonderboard (after
tearing off 3 layers of *poor* quality linoleum to help with floor height
issues).

Thanks again!

Andy S.