i think your axels will be fine, i dunno what all transmissions are better, but i think the later trannys, mk3 020s which will bolt right in are a little stronger, also 16v trannys (bolt in) are supposed to be strong, but generally they have short gears, which really won't mix well with a diesel, especially not a 1.9, you could also consider an 02a tranny, everyone seems to say they are very strong, but it requires some work since they have a hydraulic clutch and are cable shift