I am looking to buy a new ring and pinion set and posi unit for my 1998 8.8" rear end. My question is, what is the spline count for my particular rear end. I currently have 3.55 and am wanting to go to 3.90. Thanks.....

 

Don't really know what size truck you have. I believe the ranger is 28 and the full size is 31. Others know more than I, if you post more info they might help.

 

8.8" in a Ranger= 28 spline.
8.8" in a F-150= 31 spline.

 

Sorry, guys. I have an F150. 31 spine it is. Thanks

 

Hey radjks I just had my 8.8 rebuilt from the ground up due to a bad pinion seal and total loss of lube in the diff. But the rear end has 31 splines and the front of all 4x4 F-150 and expeditions have 28 splines in the diff no matter what engine size or rear end size. If you have not already had the work done I would go with the Eaton L/S unit, I did and love it. A world of difference from the stock unit. And the eaton is rebuildable.

 

im glad to have found this post, i just got a 2000 f150 4x4, and traded in a 2000 ranger . i had bought a limited slip carrier for the ranger but had not gotten it installed yet. would i be able to use this in my front diff? that would be all the streetable traction a man could ask for to have limited slips front AND rear. would it work, the limited slip unit i have is out of a 95 mustang cobra.

 

I'm nut for sure what kind of L/S unit you have. Not for sure how it will perform in the frt. axle of a vehicle that is driven daily. I have heard many skeptical stories, reccomending not to put a L/S in the frt. axle of a truck that is driven daily on the highway.

Looking at a Dyneer (tractech) catalog appl. the Detroit Locker used in the frt. of an 8.8" IFS is also used in the Rear of a 28-spl. 8.8" in a Ranger--they are the same part# 187C-147A.

Detroit now makes a "True-trac" for the 8.8" frt. axle in an F-150 (p/n: 913A-447X). True-trac for the rear 8.8" 28-spl. is 913A-361.
I believe there is something different in the axle gears (s-ring or retainer) between the True-trac for the front vs. rear.

I have used the True-trac in off road dirt racing with success--cannot predict how it would work on highway driven vehicle. The beauty of the True-trac: it is like having two differentials in the frt. of your vehicle. Both frt. wheels will pully independantly and seperately at different speeds.