For the B44:
For some of the racers at my track that break shock shafts frequently, I get T4 shock shafts, cut them to B44 length, and use a die to cut larger 5-40 threads. Strengthens the whole front end. The Rpm small B4/T4 bumper can fit onto the B44 for a little bit more protection. Arms are only $6.00 and easy to replace.
The diff gears strip out after a few months of racing, there are just plastic gears. Make sure the cvd's are shimmed all the way out to prevent the bone from putting excess upward pressure on the diff outdrive when the suspension is fully compressed. you can see where the bone rubs on the inside of the outdrive cup. Make sure your transmission case stays nice and tight, and actually adjust your slipper clutch for track conditions (not just the 10mm it says in the instructions). Gears are only $7.00, and should be replaced pretty much when you rebuild your diff.