jesse,
do you ever Race at the Gate in Cleveland, Ohio? They have one at the track hobbyshop and its cheap, $289 plus tax. They also have the Fk lightweight diff if your racing on carpet.
Ray
On the bearings-I agree-dont clean-em out when new-just run them. Rip is NOT an issue with this car. If your not fast with this car-its not the bearings. To prove it-after a run or two on the car-take out the outdrive bearing, pop in the diff and spin it!!! It'll spin so fast and so long.