Is the hub bad?
If it's the studs they are screw-in for the stock Jag hubs. The thread is the same as the outer portion - 1/2-20 if memory (?) serves. You need to grind or chisel off the staked-over area on the inner or differential side and unscrew them.
New studs are (fairly) readily available as they fit a whole bunch of years.
The hard part is re-staking the inner ends after the new studs are screwed in. Takes a pretty big press or hammer
Another possibility is to pick up a hub at a wrecking yard. I've had pretty good success with that as long as I could see them before I bought them. If you go that route, be sure to get the spacers so the bearing free play can be set correctly - as explained in the ERA manual. You may still have to buy some different thickness spacers depending on how the the hub & upright go together.
Tom