40 Rear Axle Seal and Bearing Compatibility

TundraTex

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Apr 24, 2019
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Location
Allentown, PA
I've looked all over and haven't been able to find anything conclusive, so I thought I would just make a post to ask the question and establish a concrete answer. When I look online at rear axle seals and bearings they appear to be split into pre-73 and post-73 packages. Reading online the pre-73 packages have brass or metal seals and the bearings have inner races that are pressed onto the axle shaft. Whereas the post-73 packages have a rubber seal and bearing without inner race (axle acts as inner race).

Can you pull the pre-73 bearing and seal and replace them with a post-73 bearing and seal?

I am asking because I am rebuilding a 72, but I have complete axle assemblies from a 1978 (12/78) and an 1980 (11/79) FJ40. The axle housing for the 72 are in the best shape of all of them. So I'm planning on using '72 housing with the front disc components and axles from the '78 and the diff and pinon from the '80 for the 3.7 gearing and fine splines. On the rear I was originally planning on just using the '80 rear end, so I went ahead and ordered the axle rebuild kit for it. However after getting a good look at it during disassembly, the housing is pitted pretty badly with a lot of rust, whereas the '72 is in really good shape. So I'd like to go ahead and use the '72 housing with the diff, pinon and axle from the '80 with a disk conversion kit. But I'm just needing to know if I can use the seal and bearings I ordered for the '80 axle, or if I need to go ahead and just order the '72 seal and bearing. I will note that the '72 currently has the older style metal seals, but appears to have a later model bearing in it, as the axle does not have an inner race pressed onto it. But it's completely possible that this is wrong based on some of the other things I found when I was disassembling everything.
 
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TundraTex

SILVER Star
Joined
Apr 24, 2019
Messages
15
Location
Allentown, PA
Thanks guys! I was in meetings all day and so I figured I would just go ahead and ask the questions in case anybody might know off hand. Plus I figured it would be a good thing to have documented somewhere.

But I did just get off the phone with those guys and they said that there were some slight differences in the axle housing and the later setup would not work. So I bought pre-73 seals and bearings from them to go along with the post-73 seals and bearings that I bought from them previously. I plan on going ahead and pulling the seals and bearings from both sets of axles and I'll post up the difference between them so that everyone can enjoy.
 
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