the getrag is indeed available with both long and short input shafts.
the short input is (thankfully) even rarer than the long input.
the short input shaft is for use with the duel mass flywheel, and the long input is for the single mass flywheel.
therefore, if the op is shooting for big power, and requires the single mass flywheel, he should be looking for the more available LONG INPUT box.
they are easy to identify, if you stand the box on its bell housing, the short input box will not rock, because the short input shaft does not protrude.
the long input box will not stand upright because the long input shaft protrudes out past the bell housing.