I've been told my A4 (03 1.9TDI Quattro Avant) needs a new brake servo. Is there any difference between ATE type and TRW - as in does one type need to be replaced like-for-like? And if so, is there a way to identify which my car has without pulling the old one to check the part number? I'd like to have the parts ready before starting the work. Any help would be much appreciated.