Hello Everyone,

I have a 1999 F-150 5.4 and am thinking about changing gears. I currently have a open 3.73 differential. I want to go to a LS or possibly a locker, this truck is mainly used for driving back and forth to work, so a LS will probably be better. I want to switch gearing because the rear pinion seal needs replaced and Ford wants $500 to fix it, so I figured I would change the gears and add a LS thru someone else and it would be a given to have a new pinion seal. Here's the question. What front axle do I have? I've heard that it's the 8.8 front, but I'm not for sure. Also, will 4.10's really make that much difference or should I go to 4.56's? The truck will eventually (2 yrs or so) be slightly lifted and be sporting 33's. The truck doesn't see much highway, so mileage isn't really an issue. Sorry this is so long. Thanks in advance for the help.

 

yes you have a 8.8 rev cut IFS front axle, i would recomend 4.10 if you are going with 33" tires in the future, 4.56 is alittle to much gearing in my opinion for 33" but if it never sees the highway than it might be right for you but the rpms would be up there, good luck

 

I'm looking for a limited slip front end to, I know it is 28 spline, but does it have to be just for IFS, and rev cut, or will any 8.8 28 spline LS unit work?

 

Thanks for the help Bigtruck311. I do some stock truck pulls at the local fairs and festivals and have a real problem with tire spin so I'm hoping the LS will help out. I'm sure if I go to 4.56's it will be even worse. Thanks again.