I have a 2005 F150 4.6 2x4 with 3.55 and no limited slip. I want to do some off roading but with my current setup I have problems from time to time. I was recommended going with a Auburn Gear HP limited slip differentioals. Can some one help me identify which one I need? And do you guys agree the Auburn HP diff is a good set up?



http://www.auburngear.com/aftermarke...t.asp?page=hps

 

OK digging through some more threads and found this remark:

"All F-150's with 9" and 8.8" produced 1976 and after should be 31-spline axle. To my knowledge Mustangs and Rangers with the 8.8" are 28-spline. My 94 Ranger with 8.8" is 28-spline."

With that being said it looks like I need part # 542025.

Can anyone confirm this?

 

I thought it was 31 spline for a REAR axle 8.8 and 21 Spline for an IFS 8.8??