the easiest way to get your org. wheels to match up is to take one with you when your shopping for a new rear; make sure they fit. the bolt patterns used in 46 are still used today... hell, toyota truck wheels fit mine!!!

If you cant find an axle w/ the same bolt pattern you can also get a wheel spacer/adapter. but this will increase your track about 1" on each side. you can also use one of these if you find an axle that is 2" narrower than your org....