I have never done rear differential work and mine is leaking. Is there a gasket that most likely needs replacing?

What year and model is the car?

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On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

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noel,

i'm just speaking from my experience on my 87 300D Turbo. if its leaking from the rear part where the diff housing plate (not sure what the right term is), then that's an easy fix. the difficult thing is removing this beast from the subframe!

re leak: mine was leaking on an old, replacement diff that I bought, so after 2 attempts at trying to bolt it tighter, they ended up resealing it with Permatex Grey RTV sealant. i did the same on my Toyota 4runner's rear diff when I installed a locker in it.

To remove the diff, you'll need XZN sockets (aka triple square, 12 point sockets) to remove the half shafts from the sides of the differential. can't remember what size, sorry. then you'll need to disconnect the flex disc and drive shaft from the front of the diff. lastly, you'll need to unbolt the bolts holding the diff to the subframe.

what's tricky is that the diff's shape is not conducive to it being held up by a jack. mine almost fell off the jack when i was lowering it.

check in my post history or my blog. i may have a writeup or pics somewhere.

lastly, please follow all safety precautions when removing the diff. that thing is heavier than you think.

72 280 SE 4.5. Thanks and sorry about that.

Now we can answer.

You do not have a plate, as you have a Swing Axle.

The most common/possible Leaks On Swing Axles are :
Front Seal
Fittings on the cooling tube.
Possible axle Boot on right side.

The very first suspect on these is the Vent/Filter is plugged.

Take it off and clean it in Kero. If it was plugged , then there was undue pressure in the diff, making it leak thru the seals.

Also, the diff level must be checked with the enclosed axle tubes LEVEL, not on a lift. It they are not level for checking fill, then when someone tops it off, there will be an over-fill condition, causing leaks.
Check the level plug when checking the Vent assembly.
You want just below the level plug. { I just use my pinky finger]

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A Dalton

Thanks Dalton!