got an 02' f150 fx4 excab 4x4

pretty sure that I have the 9.75? (axle code 19 on the door jam =3.55 non limited slip)


the owners manual states to use 75w90 in the front axle & 75w140 in the rear.

BUT, the tag on the rear axle states to use only 75w90....which is correct?

leaning towards moble1...just trying to get the correct weight in the right area

 

Ford has changed their recommendations to the 75W140 for rear diffs. Don't forget the friction modifier if you have a limited slip.

 

The correct oil to use is full synthetic 75W140 in the rear and conventional 80W90 in the front. However, you may use synthetic 75W90 in the front. Yes, your rear is the 9.75 if you have a 5.4. The factory uses RTV sealant, but you may use a conventional gasket if you prefer.

If you do not have the stock gears or an aftermarket locker/limited slip, you must use what the gear manufacturer specifies, not Ford.

 

thanks for the quick replies

to my knowledge everything is factory. 2 prior owners.
In the process of changing all fluids.
already did fuel filter and T-stat and coolant & serp belt

tranny flush and filter change along with T case is next on the list...after that, the pumpkins.

would it be better to flush with out the filter change and after a few miles swap the filter...or do the filter with the flush and then do another filter after a few miles?

 

I really don't see the need to change the tranny filter, it's just a screen. I'd recommend taking it in to a shop that has a fluid exchange machine. Just get the fluid exchanged, don't let them use any kind of "flushing fluid". Make sure they use a Mercon V fluid, the only "universal" fluid I'd trust would be one of the high end synthetics.