Foxbody Pinion Seal: DIY-able?

After spending some quality time under my '90 Foxbody GT replacing the fuel pump and filter, I noticed a small but noticeable amount of oil that seems to have come from the pinion seal.

Looking online, it seems like replacing the seal is just a matter of 1) dropping the driveshaft, 2) removing the nut, 3) pulling the flange, 4) replacing the seal and 5) put it all back together the way it came out. We are talking a <$10 part. What I read said to mark everything and put it back in the exact same orientation it was in originally, including the pinion nut itself.

My worry comes from the fact that I know the torque on that nut is an important factor of the whole ring and pinion clearance thing, that is honestly black magic to me. Is it fine to remove the pinion nut and just tighten it back down to the exact place it was when I started?

Is this something that needs to go to a driveline shop? Or would I be better off just topping off the differential at every oil change and living with it? (it's not that much oil)

SEADave wrote: My worry comes from the fact that I know the torque on that nut is an important factor of the whole ring and pinion clearance thing, that is honestly black magic to me. Is it fine to remove the pinion nut and just tighten it back down to the exact place it was when I started?

Yes, it's fine to do that.

IIRC, the crush washer needs like 250lb ft to crush the right amount. I tried a ring and pinion install myself but failed to get the crush washer torqued right. I had to take it to a shop.

But I was replacing the gears with aftermarket parts. I think you'll be fine if you are just taking the rear end apart to replace the pinion seal.

Tightening the nut pulls the bearings together and crushes the crush sleeve between them, which sets the bearing clearance/preload. If you mark the nut and shaft (and flange just to be sure) with a center punch and put them back where they were nothing will change for all practical purposes.

If I remember right the other way to do it, which the factory book will probably outline, is to crank the nut down until it takes a specified torque to turn the pinion with the axle assembled and the brakes removed (use a beam type 1/4" drive torque wrench). Doing it that way will crush the sleeve a little more if there's any wear in the bearings.