Dodge 3/4 Axle History

[Forgotten Field]

Some questions and the story behind them:

When were the changes made between the early rears and later rears? My understanding is that the early rears are 8 5/8" and the later ones are more than 9". Is this correct? Are all bolt-on differential covers indicative of the earlier rears? Are all welded-on differential covers indicative of the later rears?

Here's my problem. I bought a running 1943 WC-52 for a customer at an auction. We found that the front rear was disconnected (no drive shaft, no drive axles, and no brakes) so it could not use 4WD. I have multiple spares and decided to remove a steering rear from a WC-55 to overhaul off the truck and replace the steering rear on the front of the WC-52. Today, when were were working on the WC-52, we found that the rear on it has a welded differential cover and the front is a bolt-on type.

Since the last owner of the WC-52 is deceased, I have no way of asking him what's going on. But what I am thinking is he had to replace the front axle on the WC, did so, then discovered it had the wrong ratios, so disconnected it to be able to run and drive the truck.

So before I go further and remove the rear axle off the WC-55 to have a matching set under the WC-52, I am asking here if I need to worry about this at all, try to re-hook up the steering rear on the truck, and make it work. Or, if the steering rear and rear are different, if there is a better way than taking a set of axle housings off the WC-55 and putting complete, known matching axle set under the truck.

I am leaning towards using the WC-55 front and rear axles complete to solve this problem, but welcome any advice. Thanks!

[JBizal]

The axle change occurred at serial number 81657582 with a few exceptions. This serial number sequence is roughly mid 1943 not to long after the beginning of July.
Early axles used the 8 3/4", later used 9 5/8". Ratio was the same, so you can have a large R&P axle assembly in either front or the rear and a smaller the same way. Will not hurt anything.
John

[Kaegi]

I would, and do, use the larger type in both front and rear. they never fail. the 8.75" fail with broken teeth usually. that is why 6 months into 3/4 ton production the switched to the 9.625" diffs. and never looked back

[June J]

Hi,
its quite common practice for folks to change the 8 3/4 gear sets from 5.88 :1 ratios to 4.98:1 ratios by installing 1/2 ton gear sets. If, then, the frond diff had a different ratio to the rear diff then that may explain the removal for the drive shaft and axle shafts. Its also possible that the front diff has been assembled incorrectly with the ring gear on the wrong side of the pinion thus causing the wheels to turn in opposite rotations.

To check the ratio, mark a tyre at the 12.00 o'clock position, then turn the input yoke by hand counting the number of turns of the pinion it takes to get 1 turn of the wheel, bingo. Then at lease you will know what your dealing with.

Then jack up both front and rear axles and rotate the rear drive shaft to establish the rotation for forward/reverse and compare to the front axle.

I owned a WC 57 for 11 years, she ha the 8 3/4" differentials, and apart from a carrier coming loose, I had no problems. I did do some reasonably tough off road work but never towed a trailer.

Cheers
Ian