I have a 1992 F150, RWD, 5spd, Inline 4.9

I need to identify what type differential is in this truck in order to change the fluid.

Apparently there is a difference in which fluids and weight to use, and limited slip and friction modifier additive.

How can I for sure identify which rearend is in my truck to determine what fluid to use?

 

Drivers side door jamb sticker will give you an axle code. post this code or google it and it will tell you what axle it has. If your door jamb sticker is missing there should be a metal tag under one of the cover bolts...this will also have your rear end info on it.

 

If in doubt or info is not available Just use a synthetic 75/140 that has the LS additive already in it will be noted on the container. This will cover all bases. Note it does not effect a non LS diff. to run a lube that has the LS additive in it.
Note 2 for front diff. in 4x4 use 75/90 lube either conventional or synthetic.

 

I took a screenshot of the tag......Axle Type 19


I googled it and did not really find what I need to know.........type, fluids to use/not use, etc

Can you please assist me?

 

It's a 3:55 open differential

No need for friction modifiers because there is no limited slip.

Manual calls for 80w90 gear oil.

 

thanks so much

 

sorry if this is a bump but i was wondering what my differential is so i can change the fluid as well axle code is 18 according to the door tag 1994 f150 xl 4.9

 

Same fluid as above. You have an 8.8" rear diff with open carrier and 3:08 gears.
They're all 8.8" - 18 stands for 3:08 - and if it were trac lok it would have a letter (H18)

 

Oldie but goodie post.

I'm moving on to changing out the differential fluid on my 1991 Ford F-150 with Axle 19 code listed on the door jamb sticker.

From what I've seen on this forum I have a: Axle: Ford 8.8 Capacity: 3800 Gear Ratio: 3.55 - Non-limited slip. - Non-limited slip does not require the friction modifier, correct? Using either 75W-90 or 80W-90 fluid?

Thanks.

 

Yeah axle code 19 is 3.55 open. So no friction modifier is needed, and I'd say 80w-90 GL5 is the usual recommended fluid for an 8.8.