Maybe they are talking about the bell housing? Not sure. Basically if the box is from another 2WD 1.8T golf, leon or A3 if should fit. But you need to look out for the gear linkage design. You can fit a later gearbox, but you'd need to swap the cables and gear lever box, which is obviously something you don't want to do.
The codes above were taken from the audi service data, so should all be okay for your car.