I just bought a Yamaha 250cc, it needs a new rear differential, and the brake mechanics are all torn to shreds in the rear axle, I am wondering if a rear differential and rear axle off of a 220 or 350 would work on the 250.

 

just check measurements. all of those years were swappable. timberwolf, big bear, moto4, etc. i swapped front spindles with different hubs easily. those rear ends are a dime a dozen.