1939 plymouth rearend

[Guest streetrodder]

Does anyone know how many years they used the same rearend that is in my 39 plymouth four door. I think it has about a 4.25 gear in it does that sound right. Any feedback at all would be very helpfull thank you:D

[Phill Powell]

37,38,39 diff assemblies are interchangible, common ratios are 3.9 & 4.1.

I think there are a couple of other ratios but they are rare (3.7 & 4.3?).

Other differences are 11" brakes & a cross type pinion flange(7 passenger).

Not sure if 40's diffs are interchangible, heads might.

Hope this helps.