Does anyone know the difference between 300EX, 88-89 250R, and 400EX Front Hubs? Do you know if any of these (250R & 400EX) are a direct replacement for a 300EX?

 

The only thing I know for sure is the 400 hubs are aluminium and the 300 are steel.Looking at them I would say that they should swap out with no probs, considering that they all use same bearing setup on rear I would assume fronts are same.