Hey guys I have a 2002 2wd F150...its in the shop having a Ford remanufactured tranny installed, hopefully it will be ready tomarrow morning. Anyway while everything is apart I am thinking about having the diff cover removed, inspected, and serviced. The code inside the door is H9 which should be a 3.55LS right? The problem is that it no longer acts like a LS diff, if you spin one wheel the other spins the other way like an open diff. Also I think it used to do spin both wheels but it seems like lately it only spins one. My question is this...how do I tell for sure if I have the LS, because I need to know what type of fluid to have put in. Also will a fluid exchange with new friction modifyers make if perform like it should or should it be rebuilt.

If it is a 3.55LS what will the tag on the diff say on it?

 

If it is a traction lock, the tag should say 3 L 55 next to the bolt hole. If it says just 3 55 it is an open diff.

If you do pull the cover, there will be a big s shaped spring in the center.

If it is slipping, just replace the clutches.