Well, I hate to discourage anyone from a DIY project, but out of all
the things I've tried since buying an old house, that was the worst.
Tear out the wall. Spend half the weekend shoulder deep between 16"
studs trying to get the thing to stop leaking. Resoldered the
connections, replaced the gaskets, finally flung the whole contraption
out across the yard and picked up a new one from HD. Rest of the
weekend cutting, bending, fitting. Finally, in desperation, used a
rubber coupling to fit the new drain to the old cast iron pipes. All
for a tub I don't even use! Another one is leaking now (girlfriend HAD
to fill the damn thing to the overflow, now I have to repaint the
kitchen ceiling). I'm going to fill that one with rocks and concrete
and be done with it!