For Mk2 tranny, I have an AOP, and it is a good tranny with nice gearing. My brother has an AGS in one and AWY in the other. AGS is similar to AOP only the 3rd and 4th gears are slightly different, still a pretty good gearing tranny. But what ever you do, stay clear of the AWY tranny, unless you want 4000 RPM at 75 mph. It will make your engine scream at higway speeds and lower mpg. Do not quote me, but I have read that Mk2 and Mk3 trannies are interchangable, so if you put a first gen TDI in your 85 (Jetta?), you would be able to put any Mk2 or Mk3 tranny in. Also, I have read that you can put a mechanical pump on a TDI. I do not remember which pump though. Sorry this might be vague with details, I mainly stick to Mk1 and Mk2.