‘99 F150 auto V6 regular cab lb xlt
Hi 👋 everybody I was wondering if someone knows if my truck’s diff is open or a limited slip, from what I know it’s not the 9.75 rear end like my ‘02 FX4 F150, so I’m guessing it’s the 8.8 rear end. I know on the door sticker/ tag it says “axle H9” if y’all want I can take a picture and show it just to double check. I’m asking this question because I’m having a hard time believing Ford would put a limited slip on a V6 truck. Maybe it’s so but not sure which is why I’m asking y’all. Anyways here are the photos of my truck’s 8.8 rear end (I believe it’s an 8.8 anyways) and yes evidently I don’t know much about drivetrains. Thanks for the help

Also yes not sure if this was a good idea or not but after I changed the diff gear oil I threw away the little rectangle tag that had some codes on it 🤦‍♂️🤦‍♂️🤦‍♂️

 

3.55 Limited slip... and that's an 8.8

ANY axle code with a letter in the code is limited slip.

Open diffs are a number code only.

 

When you changed the gear oil, did you put friction modifier in it?

 

Awesome! Thanks for the help! Yes and no, as in I put Valvoline Full Synthetic 75W-140 and it says it has Friction Modifier already mixed in it, but I’ve heard it’s always good to add the little bottle of friction modifier anyways. But it’s been a bit over 2 years since I’ve changed the oil and so far it seems to be holding up great no popping, or any vibrations or noises!

 

Yeah, it's much better to use the Ford XL-3 friction modifier.

 

If it's been two years since the oil was changed and there has been no chattering, worrying about adding friction modifier is the last thing to spend time or money on. It's already demonstrated it isn't needed.

 

Didn't mean now. I meant next go around. It's probably worn out though if it didn't chatter.

 

If the replacement fluid already had the modifier in it as advertised, it also wouldn't chatter.

 

Ford put LS in a buncha there v6 applications. Few of my rangers were LS so was the exploder v6 i had.