I'm wanting to put in some 4.10's on my truck. I've done some research, found out that the axle code is H9, which is the 3.55Limited Slip. Here's where my 'newbiness' comes in.

How do I find out what size rearend I've got? I've seen the 4.10 gears for the 8.8", but not sure if this is the size I've got on this truck.

Also, can someone clue me in on what exactly limited slip means? Is this the same way of saying Posi-trac?

Tks in advance,

D

 

The 5.4L has a 9.75" rear end. The other F-150s receive an 8.8" rear.

Limited slip means that the differential has clutch-packs that limit the amount of wheel spin when a tire loses traction. If one wheel starts to spin, power is then transfered to the other wheel. It goes back and forth trying to keep the power balance even so that the vehicle continues on in a straight line.

An open differential, on the other hand applies power to the wheel with the least resistance.

Ford actually calls their unit a Trac-Loc differential.