Mopar rear axle spotter's guideYKSITYISET SIVUT

https://www.crankshaftcoalition.com/wiki/Mopar_rear_axle_spotter%27s_guide

Casting numbers

These may not be all the casting numbers that were ever used on the various axles, but are a starting point:

7-1/4" 2070051 3507881 3723675

8-1/4" 2852905 3723598 3723599

8-3/4" 1820657 (small pinion shaft, up to 1964) 2070741 (small pinion shaft, 1965 to about 1972) 2070742 (large pinion shaft, 1957 to 1968) 2881489 (tapered pinion shaft, 1969 to about 1974)

9-1/4" 3507890 3507891 3723199

Rear axle dimensions