Diff Gears

[CruzenLuke]

Is there no way too just find some diff gears? I dont want to swap out my axle but i am running 4.10 I actually love the truck the way it is but its extremely dangerous driving 35-40 on the highway in my area. If i really have to swap the axle with what specific model vehicles are compatible with the truck?

[Merle Coggins]

You should be able to get 55+ out of your truck with the 4.10 gears, although the engine will be close to max. RPM's. Replacement gear sets for these axles are non-existent. You can find a differential assembly from a Plymouth, Dodge, DeSoto, or Chrysler car from the same era, that has a suitable gear ratio. There was a change in spline count for the axle shafts and side gears some time in the early 50's, but otherwise they're a direct swap. I have a 3.73 diff from a '50 Plymouth in my truck. Or you'll have to go with a more modern axle from a Jeep Cherokee, or similar. I have no experience with this type of swap but I've seen many here that have done it. The Cherokee seems to be the favored one. 

[David A.]

I too replaced the 4.10 center section in my 50 B2B with a 3.54 out of a 48 Plymouth. As Merle stated the axle spline count changed sometime later, but I’m not sure when. For me it was an easy direct swap. 

[kencombs]

Just to echo the above, the center sections swap for many years better ratios are available.   especially true for 54 an up as they were starting to set the cars up for the better roads.   Swapping axle gears to match splines is easy to do.   And swapping just the center section complete is so much easier/faster than setting up a ring and pinion, at least for me.

[Jim Shepard]

I think these gears are extremely hard to locate now. I looked for several years. I ended up going with a 1997 Ford Ranger (same lug pattern) 3.73 axle. Other than re-positioning the spring perches it was pretty straight forward.

Edited January 9 by Jim Shepard

[ggdad1951]

My B3D goes 60 MPH all day long on my 4.10 gears....engine tach says I am below danger RPM by a comfortable margin (but I also have taller tires than you likley).  At that speed I'm more worried about steering and braking with the "smart" people driving modern vehicles wilst on their cell phone than engine RPM.

[Plymouthy Adams]

14 hours ago, David A. said:

I too replaced the 4.10 center section in my 50 B2B with a 3.54 out of a 48 Plymouth. As Merle stated the axle spline count changed sometime later, but I’m not sure when. For me it was an easy direct swap. 

what 48 Plymouth had a 3.54 rear gear?      If you found that in a 48 Plymouth, likely it was transplanted earlier by a PO.  

[David A.]

My apologies for the wrong information. I looked back through my old paperwork, and it was advertised as being out of a 48 Chrysler. I don’t know why I had it in my head it was a Plymouth. Thanks for catching my mistake!

Edited January 10 by David A.

[Desotodav]

I swapped the factory 4.1 diff centre in my 52 truck out with a 3.54 diff centre from a 54 Dodge car. I had a few diffs to choose from, but the one with the correct spline count was easiest.

i also did the same with my 53 truck, but ended up using the car diff centre with different spline count and changing out the side gears to suit.

I did find that the car diffs (here in Oz) were about 3 inches narrower than the truck diffs, and I suspect this to be the same in your part of the world… just in case you had thoughts of changing the whole assembly ?