If you just want to get rid of the stock bushings and throw on some regular bearings:

Duratrax Pno: DTXC1523 (5 x 8mm)

These are the same small bearings (x2) that go on the out-drives for the differentials. *not the big ones that nest the diffs to the bulkheads*

Also, an aluminum tension kit from YeahRacing comes with bearings. Pno: #SPT2-038OR
Hope this helps.