Arnie Goetchius wrote:

SNIP
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

That may look like 1 1/2" copper, but it is probably 2" trade size.
Anyway, there is a Fernco coupling made specifically to couple
PVC to copper sizes. Probably have to go to a supply house, not HD.

Jim