I need to replace an old Delta single handle "crystal ball" style shower valve with a new Price Pfister valve. Trouble is, I have no access to back of shower due to another bathroom located directly behind this one.

I realize that I will probably have to cut into the fiberglass shower to make the valve hole bigger, but could use suggestions to make the job easier.

Here is a pic of the hole with existing vave and new replacement valve. And a pic of the cover plate.

http://i34.tinypic.com/rw2xyr.jpg

http://i38.tinypic.com/jkkdnt.jpg

You will have to open up the shower wall to replace the shower valve nut they make a remodel plate,(see images) to cover any holes you have to make. Good luck and thank you for rating my answer. Tom

Thanks for the input speedball, I guess my question is whether I will have enough room to solder given the hole must be smaller than the new face plate (see pic 2 right hand side).

That's the beauty of a remodel plate. It covers the larger hole you'll have to make to install the valve. Simply trace the out line of the plat5e and don't cut any more then you have to. Good luck, Tom