I just bought a 98 SST and there is a grinding noise comming from the rear. I talked to a guy at work and he said that those axles were notorious for the pinion bearing going out. Does anybody agree or have any other thoughts.

 

If it has the Chrysler 9.25 rear diff. then yes it seems to be a common problem. I know of several that have had those problems including myself. Mine is a 01' and I have replaced the pinion bearing as well as the clutch pack for the trac-loc. Truck currently has 151,000 + on it.

 

I've heard of the LSDs breaking a lot, but never heard of the pinion bearing problem with the Chrysler 9.25s.

 

the 9.25 open is fine. the LSD is crap, with broken pieces floating around.
remove the cover and see what you find.
http://www.pavementsucks.com/tech/diff.php

 

How do you tell what size you have? I know I have 4.10 gears. My yruck is a 2500.

 

its all in how you take care of them service them and use the right oils and friction modifiers i work in a garage 90% of people neglect the vechicle's