The codes off the tag are S828D and 55 88 1E08. It's a 01 F-150

 

What is the axle code on the door jamb?

 

It's H9

 

Yes, LS with 3.55s. same as what I have.

F-150:
19 – 3.55 Non-LS
18 – 3.08 Non-LS
H9 – 3.55 LS
B6 – 3.73 LS

 

Thanks Bluejay. Changing the rear diff fluid and wanted to make sure.

 

Ok, good luck. Just for future reference, there is a pretty comprehensive decoder list in the Articles and How To section.

 

Great! No info and rear diff fluid change though. I'm good to go,just don't want to leave any stone unturned.

 

75W140 full synthetic, and a bottle of friction modifier if the fluid you buy doesn't already have it in it.

 

Ordered Amsoil 75/140,waiting to hear from them if it has the modifier in it. have a bottle from Ford already if it doesn't.

 

It does not, they sell their own modifier. Use the Ford modifier if you already have it.

 

Thanks folks

 

Now I'm really confused. I just got an e-mail back from Amsoil and they state that "The Severe Gear oils do in fact have the necessary additives already blended into for a limited slip differential".Would it hurt to throw in the Ford modifier with it?

 

Run it without, leaving room to add it later if you have to, and if you experience ANY chatter, put it in.

 

+1 I bought my truck used and it had some rear end chatter and all I needed was a few ounces of additive.

 

Does the friction modifier make the clutch slip more easily or less?

My 2010 F150 with less than 1000 miles and a 3.73 has a little LS clutch chatter when doing a full lock turn on pavement at low speed. It's not very noticeable. Is this a problem?