I have a 742 center section rear axle with a leaking pinion seal.
1. The FSM says to use a special tool to set seal depth when installing a new seal. Do I need it? Is the a shadetree way to get the seal depth right?
2. Will I be able to replace the yoke after the seal replacement without affecting bearing preload?
3. How do you torque the nut holding the yoke properly?

TIA

Dennis

1. Ignore all that and just install the seal. I never heard of seal depth specs.
2. 742 has shims and no crush sleeve so you can't mess up preload. Reinstall nut tight, IIRC service manual says 240 ft lbs.
3. big pipe wrench

I think the most important thing to do is to get the right seal. I had a leak on my 742 rear and just picked up a seal from Advance Auto, which uses leather as the inner seal material, and before long it was leaking again.

At the least, get #18880 from NAPA, it is also cheaper than the leather style and is made of neoprene. I have also read on here that the seal Cass (Dr Diff) sells is even better than the NAPA one.

Good news is, as mentioned above, the 742 is a really easy one to change.

Darren

Dr Diff has the better seal

or the napa one #18880

hold the yoke with a pipe wrench and use a socket on the nut and tighten it up

use some lock tight on the nut also IMO

In the past I have used a scribe and marked the nut and pinion shaft, and counted the exposed # of threads and then just put it back where it was after replacing the seal.

Thanks for the great suggestions.