Hey guys and gals.

I'm having trouble figuring out what weight of rear end oil to use and if my truck is a limited slip or not.

I have a 1996 f150 2wd. The tag on the rear end has the following numbers and letters: S838M 3 55 88 5A03

And inside the door on the tag it has the number 19 under the word axle.

I'm kinda confused why my owners manual doesn't just come out and tell me.

Any help would be greatly appreciated.

 

im pretty sure its 3.55 for the gears, not 100% certain, and im not sure if its limited slip or not

 

3.55 gears, not limited slip according to the axle tag. 80/90 works.

 

The Ford 8.8" rear is pretty forgiving, in my owners manual it calls for 75w-90 unless you tow, then I'd run 75w-140. If you run a quality Synthetic oil or use Lucas Oil Stabilizer, you don't need to add friction modifier (if it was a limited slip).

 

For a factory limited slip the axle code on the door will start with a letter and there will be a L between the first and second number for the axle ratio, ie. 3L55 for limited slip and 3 55 for open.

 

Thanks everyone for the replies. I'm sure I have a open rear end.