smalltownspeed

What are the diffrences between a rearend from a 03 F-150 4x4, and the rearend from a 01 f-150 lightning? Do they have the same gears? Are they stronger? Ive got an 03 F-150 4x4 pre-runner, and Im adding a set of deavers, custom shackles and a bed cage, and the guy Im buying that from is offering me the rear end from his lightning too.

Also, whats out there for my front diff? Im not sure if its a limited slip or not, but if its not, Ill want to add one, and eventualy Ill want to re-gear to something around 4.88's(Ive got 37's). What do yall recommend?



Oh, Im Cory; and this is the first "new(er)" truck Ive ever owned. Ive been very into traditional hot rods and customs for quite a while, and also have a moto-x background too. Ive got decent fab skills, and pretty strong mechanical background, but I know very little about these newer trucks...

Jefk

well,i believe that the lightning uses a 9.75" case and fords lmt slip with either a 3.55 or 3.73 gear ratio. most f150's that ive seen have the 8.8 case but 01 and 03 were the same body style, so it should work theoretically as long as it is the right spline which is gonna be 31 or 28 and make sure you know the case size. but i would get something like a spartan locker myself so i can have traction in both rear wheels like posi-trac, and if you don't know about lockers, they are basically positive rear ends but when turning, it can still differentiate like a open rear-end so you don't tear up the tires. you can put lockers in the front too but at the cost of a wider turning radius.

ol_red_2

not all f150s have the 8.8. I've had 2 of these trucks one 2wd and one 4wd. both had 9.75 ring gear with 3.55

charliedyal

You can check the axle code in your driver door jamb or the tags on the rear end to determine the size and ratio. Or you can simply count the bolts on the diff cover. 10 bolts= 8.8, 12= 9.75. The axle code in the door jamb will tell you if its LS. Cross reference the code.

Rear 9.75 has 34 spline axles
Rear 8.8 has 31 splines
Front always has a 28 spline 8.8 open diff.

As far as the lightning axle, I'm not sure which comes in it. If you already have a 9.75, I wouldn't bother with it. your regearing anyway and you can add LS's front & rear at that time.

charliedyal

And remember that if you do swap to the lightning axle, make sure it has the same ratio in it as your old axle. You go and lock it in 4x with mismatch ratios front and rear your going to destroy your t-case

charliedyal

SON OF A B!! Jefk. Please stop replying to posts that are 7 years old!! I bet this dude got rid of that truck years ago!

02sport4

He is probably just using the search feature that everyone is always yelling about

charliedyal

Yeah, figured that. But I'd still like to "lovingly" give him a good smack in the back of the head. ::dumbass::: ;-)

Jefk

that love gets around doesnt it? lol why dnt we all go to the local pub and kick back alittle

i'll paymore attention to the dates, just a noob error

Jefk

if i didnt know better ide say you had awnsered that post a couple times before yo realized it was old and got on to me. lol