Diff Inspection and Housing Gasket

[55 Fargo]

Hi all, now that the diff is out on the bench, what needs to be checked, plan on cleaning it and painting the outside portion. Are gaskets available and from where,can I use just Black permatex and no gasket and some other sealant perhaps. As soon as this is sorted out, I want to install this 3.73, and get rid of the 4.30 gears....Thanx Fred

[Tony_Urwin]

Fred, I'm no expert on these, but I can tell you that the gasket is easily available from all the usual sources. The same gasket will have different part numbers, depending on make and model (1121939, 1318011, 663474 to name a few I found on Lightning Jar). Roberts Motor Parts sells them for $5.00.

I am in the process of putting a 3.73 into my Pilothouse truck. The 3.73 pumpkin looks to be in great shape, with little or no backlash. It has a different pinion flange than my truck, so hopefully the flange from my truck be a swap. Both my 4.11 truck differential and the 3.73 car differential take 10 spline axles, so that looks good.

Good luck with your swap!

[55 Fargo]

Hi Tony, thanx for your response, if I cannot find a gasket source locally, I will make one out of the old for a pattern.

The gears look fine, they spin nicely no noises, but theere is a fair bit of backlash, not sure if I should take it into a shop for adjustment. not sure I want the thing being messed with by some intentioned mechanic, who ends up screwing it up.

Does anyone know how much backlash the diff should have...............Thanx Fred

[55 Fargo]

Does anyone know what this means.

MoToR Repair Manual lists there were 2 different Chrysler differentials, a screw on barrel differential used from 1940-1954 and a bolt-on barrel 1953-54. Probably the second one was used after 1954 but that is as far as my book goes.

[Normspeed]

Fred, as far as backlash goes, if the gears appear to be normally worn, I'd probably go with the backlash that's there. If it had been way out before, the gears would probably show some oddball wear.

The pic is from a Plymouth manual. Yours may be different.

[55 Fargo]

Hi all, pulled my axle on one side of my car today, "whew hoo", its a 10 spline the right size, the driect swap of the 3.73 hoghead should be that a direct swap.

The only thing different between the 2 diffs, was the brake backing plates, and the drums, were slightly different shaped. The axle shaft taper end and thickness is identical. My seals and bearing had grease and were not leaking.

I did discover a leaking wheel cyl, but I did suspect this one, it had not gone out of the boot yet, but was wet in there, with some leakage, so will replace both rear wheel cyls also, going to leave bearing and axle seals alone, will also use the existing end play shims......................Fred

[Tony_Urwin]

Fred, do both of your pumpkins have the same pinion flange/yoke? The 3.73 I found for my Pilothouse truck has the DeSoto flange, while the Pilothouse has a yoke. Can anyone tell me if I can swap the two?

Sorry, Fred, don't mean to steal the thread. Just seems to be the same general topic...

[55 Fargo]

Hey Tony, no need to apologize, go for it, the more the merrier. I am lucky the flanges and yokes are both the same, not sure what can be done in your case, hope someone has an answer...........Fred ps can you use the desoto drive shaft

[Merle Coggins]

I believe the flanges can be swapped. Recently I made a swap with Normspeed. I had a 4.10 out of my parts truck and he had a 3.73 in a parts car. I pulled my 4.10 and shipped it to him without the input flange because he noticed the difference in a picture that I sent him. I now have the 3.73 from his parts car, without the flange. I haven't yet tried to install it in my truck, but it looks like it'll go. The only thing I'm not sure of, is the axle splines. The one I took out of the parts truck is a 16 spline, as is the one from Norm. I'm not sure what's in my project truck though.

Merle

[55 Fargo]

What year is the project truck, if it is 1952 or later, and it has the original diff, then it may vvery well be a 16 spline, you could always use the axles, backing plates and drums if they fit off the parts truck diif and use them on the project truck. To help your curiosity, go measure the out side of the diff housing, from say the axle end flange to the centre of the pumpkin, compare measurements. Or lift the project truck up, pull one drum and bacing plate, then pull the axle and compare. That would only take about anhour, that way you know ahead of time............Fred

[Merle Coggins]

Both my project truck and parts truck are '50 3/4 ton. Seems that everyone says the 16 spline started in '53 (on the cars) but then why would my 1950 parts truck have a 16 spline? Maybe a axle swap at one time? Even if my project truck is a 10 spline, I could probably use the axle shafts from the parts truck with the diff from Norm and I'll be good to go. I hope to get at it soon to find out.

Merle