I changed the differenital fluid this weekend. C-Clips are A-OK. But.... As I was laying there I saw some grease on my gas tank, after a closer look the pinion seal appears to be at the begining stages of failing. I was at the dealership a couple weeks ago just before my 3/36 ran out and asked them to check over the truck, obviously they missed this. Not sure if the pinion seal will be part of the 7/70 drive train, but I either way they better fix it given they were to "check over" the truck.

 

I thought the pinion seal was on the differential. Wouldn't that put it aft of the tank?

 

As the drive shaft/yoke spins it tosses the lube onto the rear part of the tank, underside of bed.

 

Ah.

 

oh, that might be why my under body has a black grease on it?

 

^^ no, it's because you have a red truck.

 

Highly likely. It would be under the bed directly above where the drive shaft meets the differenital, and you would see some on your gas tank as well as on the differential near the drive shaft. When it gets worse you will have drips in your driveway.