The pinion yoke has a groove worn in it causing the pinion seal to leak. We put a new seal in a couple of years ago and it has held up till now. There was a drip under the truck this morning so in went another seal. I haven't tried it out to see if it still leaks but it's still temporary. Has anybody used a redi-sleeve on the pinion yoke? NATIONAL 99181 is on Rockauto for 20 bucks.

 

These are a good option, just have to make sure that the shaft is smooth,no lips or burrs,and that the new seal will run close to the middle of the seal when installed. Getting the pinion preload correct again can be a trick.

 

Lots of people use reddi sleeves, thats what they are made for.

Make sure you clean up the splines on the yoke and the pinion and apply a thread sealer. The gear oil can creep up the splines and leak out from under the nut as well as the seal. So check to see if thats where its actually coming from.

If you clean up the nut and pinion shaft you can mark them with a line. Then count the turns taking the nut off, and tighten it the same number of turns going back on. Use the line to put the nut at the same place and the preload should be the same.