here i'll drop some knowledge on hpi driveshafts
pro4 US came with cvd's. everywhere else came with universals.
cyclone comes exclusively with universals (us/etc).
pro 4 bones are longer than cyclone bones. they are NOT interchangeable.
cyclone bones and tamiya bones are the same length (cant remember if cyclone is 44 or 42)
hpi uses a different size pin on the bone that goes into the outdrive, than hpi.
therefore none of the universal stuff is interchangeable between cars.
hpi steering knuckles and hub carriers use a 5x10 bearing. tamiya uses a 5x9 bearing.
therefore you should only have to replace axle bearings (and perhaps shimming)_ when switching brands of knuckles / spacers.
if you're looking for bearings you may try www.kgbracing.com/redstarbearings.php
, they will sell you just wheel bearings if you want.
im no expert, this is just the amassed info i have from this thread and from cyclone / pro4 threads. your mileage may vary