84 will be Z spoked and 81 465 will be larger hub and brake. 1980 yz250 is the same hub but with smaller axle 1981 yz250 is larger hub the same as 80 and 81 465. This basically means that you are tied to a yz250j rear hub if you want a straight replacement without modifying axles and spacers unfortunately. You could explore the possibility of using the parts offered by Ekka and Bish, but you will probably need to fettle things a little to get it to fit up properly.
