There are a number of factors besides ring gear size. How many, size, and spacing of the holes that mount the ring gear to the carrier. Can you find a pinion bearing that has the correct ID for the pinion and a matching race with the correct OD to fit the housing. Is the center of the ring gear to the rear face of the pinion close enough to where it can be shimmed to the number etched on the back of the pinion (or found in an assembly manual). If there are gears that meet these conditions then they will fit. I have read where some have said they change out the whole third member which if possible would be alot easier and probably cheaper.
