Not directly - you may have to change the swing arm along with the brake assembly (if it will fit the 250 frame) - the short answer is no. BTW, it's not a differential - it's simply a rear drive gear case - the axle is solid from one side to the other (live axle).
Also to aid in your search, the rear gear case was the same for 88-94 TRX300 - to the best of my knowledge, no other gear case is a direct swap.