The center chunks will swap. There's a cole of ways to fing the ratio. 1 is to find the serial numbers and decode them, another would be to pull the rear cover and count the teeth on the ring and pinion gears, a third way would be to find the stamped numbers on the ring gear. One more way, since the brakes are stuck, would be to pull the cover and the shafts out of the axle (easily done on a full floater) and turn the pinion and cound the number of turns to 1 turn of the ring gear.
