Originally Posted by
rmfnla
IIRC, those Treks used castings for their lugs, BBs and dropouts, so it might be easier to braze than weld...
The OP's dropout is one of the cast dropouts, but I suspect welding would be the easiest fix, provided the OP still has the other piece. Otherwise, he may need to settle for mismatched dropouts or replace both sides to match.