Hey guys, fixing to change the rear axle seals and was just wondering if anyone could help me determine which rear end I have since I see two different part #'s for rear axle seals! I have a 2004 F150 Screw XLT, 4.6 liter engine. I don't think I have the limited slip differential so my question is are all the rear axle seals for this truck the same and will I need to add any friction modifier or just the 75-140 gear oil? Thanks! Gonna start this project this weekend!

 

Trucks with 4.2L and 4.6L engines have 8.8" rear axles.

5.4 liter trucks have 9.75" rear axles.

Here's a thread on what to take apart and why when replacing rear axle seals and bearings; it's for a 9.75, but the 8.8 is very similar.

 

you have the 8.8" rear end.

Just some good quality gear oil and you'll be fine. I suggest something like Amsoil, or Royal Purple for top notch stuff. There are other oils plenty good if your lookin to save some cash. You don't think ? or you don't know you have LS dif ? You can check by reading that tin tag hanging on the dif cover. if it says something like 3LS73 then you have limited slip with a 3:73 ratio. If it just read 373, then you don't have it.

 

Thanks for the help guys! I'll check that tag and see which rearend I have.