dloudy

My I.D. label on the driver's door indicates an axle code of H9 for my truck. Couple of questions....

1. What size does this mean I have, or can you tell me where I can look to find out?
2. Does this code mean I have the trak-lock axle?

Thanks for the help....am planning to change out the differential fluid and wanted to know this before I proceed. Additionally, when I buy differential fluid....I know I have to buy synthetic. Is the XL-3 modifier neccessary, or do certain brands / types of fluid suffice without adding the modifier?

Thanks!!

Ftruck05

I'm pretty sure the H9=3.55ls. Since you have the limited slip rearend than yes the friction modifier is necessary.

Keeblerz28

H9 means you have a 3.55LS. Limited slip is the same as Traction lok, so yes you will need XL3 additive. I don't know if other brands of oil already contain an equivalent. For type of oil, check out page 293 in your owners manual.

Other forums:
http://www.ford-trucks.com/forums/86...ier-in-it.html

dloudy

Thanks guys.

I counted 12 bolts in it, so that would be equal to a 9.75", right?

Do you know of a substitute for the XL-3, instead of buying Motorcraft? Would a Redline or Amzoil synthetic require it's use as well?

Thanks again...!!

Rubicon35

i had a jeep rubicon with lockers/limited slip rear that required either dino oil plus additive or if using synthetic it didnt require the additive. I would speak with a ford tech about this. im 99% sure you dont need the additive with synthetic. i guess it probly couldnt hurt the syn oil but its worth asking not to waste money

Keeblerz28

The owners manual specifies [motorcraft] synthetic oil + friction modifier if LS. Other brands sometimes include the modifiers already.

jbhill

ford racing modifyer is better then motorcraft.

dloudy

So more than likely, my truck would have the 9.75 inch rear end?

midwestoffroad

if you use amsoil or redline you shouldnt need friction modifier "unless you experience chatter" but 99 percent dont.

Longbeach4x4

i hit a snag I just got a rear diff cover from ruff stuff and when I took the diff tag off I thought it said 3.08 but after I cleaned it all up and got a better look at it It says

top line S8454

bottom line 4 L 1 0 88 1E14

but my door says axle code H9?? Is it an LS I hope not cus I'll have to re drain it to add the additive when I took the diff cover off the markings on the diff said
4 10

also my speedo is off (personally doesn't bother me I know how much it's off so I adjust accordingly when highway patrol is around) but someone told me if my speedo is off my rps is off which will throw off my shift points I have an E4OD which I just spend 1600 to buy a remanufactured preformamce E4OD one guy told me his speedos off and he can feel his trans going in and out of OD on the high way