So there it is, J30 5lug hubs can be used easily with the entire upright, otherwise the use of a press and a few hours is required to swap races and for the DIYer it's probably more work than they can handle. This of course will only work if using Schassis rear brakes, the J30 ebrake assembly is different from the Z32 and will not bolt up the same way, plus the backing plate has to be cut off if you're going to use a larger rotor, eliminating the ability to attach the ebrake anyway.