Change rear axle 3.9 to 3.73?

[central52]

I really appreciate all the info I'm getting on whether or not to change to a 3.54 rear axle. Now, exactly how many parts are involved? Is it just the drive gear and the drive pinion? Or are there other smaller parts to be considered?

And can it be done without pulling the whole rear axle off the car? Ed P.

[Plymouthy Adams]

find the donor and swap out for the whole pumpkin..be careful of axle length and spline count..check the shaft flange for type of yolk..

[David Strieb]

all plymouth, dodge, desoto, and chrysler rear end housings were the same from 1937 to 1947, my parts book ends at 1947. The internal parts (gears and axles) may not interchange, but the assembly will bolt in w/out modification, as well as the rear brake assembly.

[Frank Elder]

So is 3.54 as low as you can go with a 3-spd fluid drive and stock engine, and still be able to climb a hill?

[Plymouthy Adams]

I think the 3.54 was common only to the M6 hi/lo range tranny prior to 1954 when this became an option gear ratio for the Plymouth