as has been previously posted you can get the hex conversion parts for the car, but to convert the rear it only takes purchasing the actual hexes to be able to run hex wheels in the rear, which jconcepts and proline make rims for b4.1 specifically but 22 rear wheels fit on the conversion.

as for the front you need the sc10rs hex steering blocks, the hex front axles, and front hexes, associated currently produces front wheels, the rb5 front wheels fit, and proline & jconcepts also make hex wheels for the front of the b4.1

http://www.teamassociated.com/news/l...12mm_Hex_Drive for the ae link

jconcepts and proline make aluminum clamping hexes for the conversion too

as for when you get the kit its setup to use bearings in the front wheels, and axle pin wheels in the rear.