Speedy Jim wrote:

Arnie Goetchius wrote:
== snipped===

The tailpiece is likely 2" copper pipe. That would be std for shower.
The copper would be soldered into a threaded fitting.
If the copper is badly corroded, it will be very thin all around.
That doesn't bode well for any quickie repair.

The copper is badly corroded all around

And unscrewing the fitings may cause even bigger headaches if this
is a tiled shower base. If it's a molded (fiberglass) base, I would
replace the drain fitting and trap.

It is molded fiberglass. To do the job right I figure I need:

- 2" PVC shower stall drain
- Some 2" sched 40 PVC pipe
- 2" P trap for shower
- flexible coupling 2" x 1 1/2 " to connect PVC to original copper

This is the kind of job where experience counts for a lot as there
are so many variables.

Agreed. I may cut the hole and take a look. After that I may call in a
plumber.

BTW, we used to think that copper waste piping had an infinite life;
turns out it is limited to 35-40 years in actual practice... :-(

Jim