Some people go with a GoKart differential, however much light, simpler, and cheaper is
Solid axle, with one wheel keyed and the other free to rotate...but what I did to give a
partial diff effect was put a split collar jammed against the wheel hub. Spins with the
axle but can rotate at a different rate to the fixed wheel.
The difference is very noticeable in the levels of tire ware.
Also yes I only have technically one wheel breaking...don't worry about it, it's fine.