Let's get our terms straight. Is it the actual hub seal that is leaking or is it leaking at the axle flange gasket? To replace the hub seal you have to remove the hub and the bearing stays in place. If the oil is leaking into your drum then there is a leak at the axle flange. Read the factory Manual. There is a gasket, an o-ring and a clamping ring and you need to measure all of your tolerances to get it right. And sometimes you have to massage things to make it right. If the bearing has started to spin, it will wear itself into the seat and then your tolerances will be off. You may have to machine the surface of the hub to get back to factory specs.
Let's not lose track here. We remove the hub with the bearing in place, but we have to remove the bearing from the hub to insert a new seal. If the bearing has spun we have to replace it as well. I was addressing the spun bearing as a cause for the premature seal failure. Tom told me he has replaced 80 of these spun bearings stating that it is the usual cause for seal failure. IMO the thickness of the Moss gasket is a likely cause for the spun bearings as it prohibits properly clamping the outer race of the bearing (as is called for in the manual).
Yeah, I gotta go with Steve on this one; a couple days ago, I was rooting through my spares to see if I already had what I needed on hand to swap in a (stock/used) 3.91:1 differential (my existing 4.10:1 may finally get those Lempert 3.54:1 gears I bought about a decade ago...).
I do have the parts I need, so it was easy to grab a caliper and measure a couple of Moss hub gaskets. They do in fact measure between .0115" and .0125" (depending on where the readings are taken). While I never measured an original, I do remember them being quite thin and brittle__clearly not enough material there that they could shred, or separate in layers.
I last replaced my hub seals around the same time as
ausmhly did, because of leaking, so I wanted to be sure I had ALL relevant parts on hand before breaking into this.
Thanks to what Steve and Richard report above, I will be taking a closer look__and measuring__the
stack-up before reassembly!