The book says '31 to '35 had 4.25" center bore, and that '36 was the first year for the 4.75".

That's good to know about the stud diameter. The books don't always tell me that. Replacement studs should be available from somewhere like BWP if not available locally. At worst I'd think you might have a little machine work to do on the hubs to accept the bigger studs. Stu

http://www.bwpindustries.com/