I want to put a limited slip in my 96 f150 5.8L automatic. I also want to change my 3.55 gears to a 4.11 set. Does this sound like a good setup and is this a difficult project? I use the truck for towing, off roadin, muddin ext.... This truck has 31 inch allterrains if you need to know.

 

Do you plan on lifting your truck and adding taller tires later on? If not you might concider going to a 3.73 or 3.91 axle ratio for running 31s. I am running 4.10s in my 84 F150 with 33" mudders and a 4" suspension lift, 4 speed manual trans with creeper gear, with 4.10s and 33s I am geared almost too low for highway speed. Even though you do have the overdrive automatic trans, your 31s with 4.10 gears would be really low geared and will adversely effect your gas mileage and highway cruising abilities. Also I hope you realize if you change your gear ratio, you will have to do it to your front and rear differentials. My 84 originally came with 3.08s and when I lifted it and stepped up to a 33" tire I had to change my gear ratio to get my power back that was lost from installing the bigger tires. The work of swapping gears out is actually pretty involved, and requires special tools and know how. The carrier and pinion bearings must be set up and shimmed to certain specs in order to insure maximum life and proper mesh of the gear teeth. Your 96, just like my 84 uses a Ford 8.8" rear axle and a Ford Twin Traction Beam front axle with a Dana 44 high pinion center section. If you insist on going to a 4.10 axle ratio, you will need to buy a different carrier housing for your front axle. On a Dana 44 there are two carriers, one is for the higher gear ratios (numerically lower) and one for the lower ratios (numerically higher) . The higher gear carrier runs from 3.92 and down, and the lower gear carrier is 3.93 and up. You will need to buy the carrier for the lower gears if your truck has 3.55s. The rear differential however uses the same carrier regardless of axle ratio. If you really want to go to a lower gear, concider running a 3.73 or 3.91... if you don't plan to go bigger than 31s. As for adding a limited slip diff to the rear, there are a ton of limited slip diffs out there to choose from: Dana Trac Lok, Dana Power Lok, Detroit Tru Trac, Eaton. The Trac Lok is probably the easiest to obtain, they were used in Rangers and Explorers that were powered by the 4.0 V6s (4.0 powered vehicles used the Ford 8.8 rear as well), 3.73 gears were very common in these vehicles as well. Basically your rear gears and limited slip diff could be picked up fairly cheaply from your local junkyard. The parts for the front you will most likely have to buy new, because 3.73s were not commonly used in the later years F-Series 1/2 tons. You mentioned you are playing in mud and doing some 4 wheeling, you might concider a locking rear diff over a limited slip, as they provide much more reliable traction in the nasty stuff than a limited slip. Hope this helps!