: During installation of our new bathroom sink faucets,
: we realized the drain stub-out (think that's what
: it's called-it's the pipe that takes the waste
: out through the wall) was rusty and jagged and now
: I can't get the "j" curved section to screw back onto
: it. Is there some way to saw off old and create new
: threads or some way to just glue a new piece to it?
: House was built in '42 and guy at home depot said we
: had "uniquely" sized pipes! yay :(

Candice,
The Home Depot guy must have meant 1-1/4" pipe when he said "uniquely" sized pipes.
That size was very common up until the sixties.
I like to remove the 1-1/4" pipe nipple with a pipe wrench and replace it with a new one.
You will note, that they still make 1-1/4" p-traps, and the tail piece drain for lav faucets, is still 1-1/4".