Anyone that has a decent surviving A3, B4, B3, or early A4 (anything that has the early cable shifter) with a few miles on it probably would be best served by updating the whole shifter setup to the newer and VASTLY superior 2000+ version. I'm not sure what all that entails on the earlier cars (the A4 is easy swap in, no modifications at all) but I know plenty of people have done it. And there still should hopefully be some donor cars out there (the parts can come from a gasser, the shifter doesn't matter!).
I mean it is laughable just how bad those early shifters get. I bought my '98 Jetta brand new, and I think my 590k mile 2000 Golf still shifts easier than that car did at 20k miles.
I just did this change on my '99.5, and it is wonderful.
I typically just use an OEM type fluid, lately it has been mostly a Febi branded product, but it just comes in a generic looking gray 1 liter bottle just like the VAG branded stuff. Just says SAE 75W GL-4 on the bottle, but it works great.
I know the later A4 cable ends can wear out and break, but [shameless product plug] Dieselgeek has an excellent easy-to-install set of replacement pieces for them so you needn't replace the whole cable.