The o2o gearbox is the one fitted in your mk2, the o2a is a cable gear shift box fitted to higher power mk3 and Passat etc. The differences are the gear linkage, clutch and flywheel, hydraulic clutch actuation, mountings and some other stuff I have forgotten. They are said to be more reliable than the o2o, but I have seen o2a boxes go wrong also. A lot of people say the o2o box is weak, if you drive a 200hp car hard even the o2a will fail sooner or later. Fit the o2a if you have time and all the parts, if not use the o2o and the engine will bolt up no problem.
Steve.
