It is leaking fluid slowly around the front part of the diff where the driveshaft connects. Can that seal be replaced without pulling the pinion? Only diff I've ever been inside of was my last 99 cobra and that was nearly 5 years ago.

 

The official answer: Not really, you're supposed to replace the crush sleeve anytime the the pinion nut and flange are removed, and reset pinion bearing preload. This involves pulling the axles and carrier to access the crush sleeve. Pain in the *** to do if you've never done one, since it takes a few special tools (and some strong arms to pull the crush sleeve down) to set up properly.

The shady, underhanded, unofficial way: Yes, you can replace the pinion seal without messing with anything else inside the housing. Count the number of threads on the pinion, get an inch pound beam type torque wrench and measure pinion preload before removing the nut. (Note, this figure will be nowhere near the factory figure, since pinion bearing preload is supposed to be checked with the carrier out of the housing. We're just doing this to get a baseline as to how tight the nut needs to be after replacing the seal and reinstalling the pinion flange) Remove the nut (1-1/8" or 1-1/16", I forget) and use a two jaw puller to ****** the pinion flange off. Use a screwdriver or a hammer and chisel or something to pry the old seal out, clean around the flange (make sure the oil slinger doesn't fall out after pulling the flange, and if it does, make sure you reinstall it before sticking the flange back on), hammer your new seal back in, put a dab of RTV sealer in the splines of the pinion flange to prevent any fluid leakage, tap it back on and run the (new) pinion nut down, rechecking your pinion preload with the inch pound torque wrench every so often until you get at or near your original figure. Be very careful at this point, since once the crush sleeve is already crushed, it's easy to crush it further, increasing pinion bearing preload which will in a best case scenario, make for some noise, and in a worst case scenario, burn the pinion bearings up. Clean up the pumpkin, check the fluid, and off you go.

Honestly, if you've never done one before, it'd be best left to someone in the know. There isn't anything particularly hard about replacing the pinion seal, it's just really easy to screw it up. Ask me how I know...

 

I'll take your word for it friend! Decided to possibly trade the truck on a new F250 PSD. I'll know for sure Wednesday.