I have a 2000 supercab 5.4 4x4 and after reasearching on hear I think I have the 9.75 rear end. But how do i know if i have 3.55 or 3.73 gears? I have no owners manual or paperwork on my truck. Also do i have limited slip or what? Thanks.

 

On the back side of the rear differential there should be an aluminum tag. clean off the tag and you will see numbers indicating the gear ratio.

You should have either the 355's or the 373's..

 

thanks i will go out and check it now.

 

well, that little tab has 975 on it, but not 355 or 373. Is there any other way to find out without counting the gears.

 

There should be two tags on the differential. One says "75W140 Synthetic only" or something to that effect, and the other will have the differential's line number, ratio, and whether it's a locker or not. It should read something like (examples only; yours will probably be different)"V942J" (that's the number used to identify what axle is being installed in the vehicle on the assembly line) and either 3L55, 355, 3L73, or 373, L designating that the axle is limited slip.

 

I dont remember seeing any nubers resembling that but i will check tomm. when its light out. Thanks

 

well i looked at the tab and i think i have 3:31's. That really stinks. My truck is a piece. I wish i had never looked dwon there. Now i have to spend a crap load of money to upgrade to gears that should be in a truck instead of a 4cyl. mustang.

 

It's alot faster to check the axle code on the driver's side door jamb sticker. If you do look on the axle tag, look on the lower of the 2 lines of information. From the left, it reads the gear ratio followed by the axle size. The "L", for limited slip, is included within the ratio numbers if applicable. Yes, 3.31s suck on a 4X4.

 

what is it going to cost me in order to get 3.73's put in front and rear. I searched on this site but i didnt find a real answer. Also do i need limited slip front and rear or a different combination such as traction lock. If anyone has a rough idea of the price for gears, LS, install kit, and install please let me know a ball park figure.

 

You just need the limited slip installed in the rear. Have you verified that you don't have it from the factory? The Ford limited slip is the trac lok. Ball park estimate for 3.73s installed front and back with a Ford LS would be about $1,500. All the parts on the rear end will be higher on the 9.75".

 

my door code shows I have the cruddy 3:31 ratio open. And the tab on the cover doesnt have any "L's" whatsoever on. I dont think I am going to be able to afford gears. I think i am going to get 305/70R16's and just hope I can fix it good enough with the 9100 tuner. I dont care about offraod capability or power increase. I would be happy with my truck performing at the stock level but with the larger tires.

 

Ok, that sounds like a good plan.

 

There is a tag on the front of the front differential also...
I would find it incredibly stupid if ford put 331's an a SC 4x4/5.4...but it would not suprise me...I'm beginning to think more and more idiots work at ford..

 

yeah me too! If i had known this truck had 3:31 gears i would have left this hunk of crap sitting on the lot. Now I am stuck with it. I just assumed that a V8 4x4 would have a better gear ratio that my previuos V6 S10. But what was i thinking?

 

Oh man-3.31's with big tires it going to SUCK. I would definatley try to change them. The only good thing about them is good gas milage-but it might not make a difference since you will have to about floor it everytime you want to move faster