"ATP" fired this volley in
:

It's a metal drain but does not appear to be a regular two piece
threaded drain. Maybe I should have said factory pre-installed, it is
not truly integral, although that is the way the cheap pans with the
drains already installed are described. The galvanized is sealed to
the metal drain with lead or epoxy.


If that's the case, you're either going to have to grind it out a bit at
a time, to make room for a two-piece drain, or you're going to tear the
whole mess out and replace the pan, OR you can cut the drain out, re-line
the pan (which means removing the surround, and is just about as big a
job as #2, and maybe messier), and install a two-piece.

How about repairing the existing tailpiece? Any clues there?

LLoyd