With the new hub being a shrink fit to the gear I question the necessity of welding it on. But I'll defer to the pro's on that. I've rebuilt other g-boxes but never a 930. Another part of the rebuild process that appears to be critical is checking the ID of the gear in the area under the new synchro hub to make sure it matches the ID under the gear teeth and hone to match if necessary. A smaller ID after the hub is shrunk on leads to needle bearing failure as witnessed by a couple DIY's on here.
