I had a similar situation when I ordered a new Dodge in August of 2000. I could not get a limited slip from the factory with the 3:55 gears. I ordered a limited slip carrier from a company in MI who specializes in that type of thing (Rieder Racing). I have had no problems at all and my truck now has 273,000 miles on it. I see no reason you would have any problems either. I did the switch myself but this is beyond the capabilities of most truck owners. The setup and clearance for the new carrier is absolutely critical to the long term reliability of the differential.

Good Luck, Paul

ford has recognized that folks want something different. The 2011 Superduties will offer the option of a new locking rear axle on their Single Rear Wheel drive trucks. It will use an on dash button that will electronically lock the rear end at speeds under 30 mph and only if it senses that you are not turning.  Since this has several inputs from other sending units on the truck ( speed and steering) I don't know if it could be retro fitted to an older truck.

The point being is that Ford feels that they can produce a better locking rear end that will hold up. So I suspect that Eaton and other reputable manufactures can also produce a serviceable product.

If my memory serves me correctly, I believe that GM has used Eaton limited slip axles on their diesel trucks. I know several guys that say they choose the GM product vs the Ford because of the performance of the GM Limited Slip.

I do know that I've had my truck stuck where I see one rear and one front tire spinning and I'm saying what happened to my LS rear end? and I have to remember it's a Limited Slip not a Locker.

Thanks everyone for the feedback.

I'm planning to install it myself. I've only ever rebuilt a diff once but I rebuild transmissions often. The only factor that will change from the OEM to the new diff is the diff carrier itself, so the ring and pinion is the same and setting up the shims on the diff bearings is the only variable. I might bring both diffs into work and use an inspection height gauge to measure the difference between the two so I can figure which shims to use on the first try. I don't have a luxurious place to work on the truck so I don't want to spend loads of time changing shims.

Regarding the 2011s it's an interesting idea. For on-road use the modern ABS systems can also stop wheelspin and for off-road use the air locker is promising.  I don't need anything quite that fancy.

FYI I'm not in love with Eaton but they're the only geared limited slip available for 10.25" Fords. It helps that I've heard good things about them.

Just last night I pulled a friend's car from an icy slope and was thinking how that easily could have been my truck considering how crappy the traction is in 2wd mode.

Dave

You will be able to get close doing what you describe but, you will still have to plan on making a least one remove and reinstall unless you are the luckiest wrench turner in the world. I did something similar when I switched mine but, I had a new truck. I measured the gear clearance on the original assembly. I pulled the shims off and placed them on the new carrier exactly as they were on the original. I then reinstalled the carrier and I only had to move one shim to the opposite side on the outer cone to get the correct clearance (which was the same as I measured on the original setup). By the way I highly recommend the folks at Rieder Racing. They are very helpful and knowledgable on what options you could consider for your truck. Just pickup the phone and call them, they will be glad to talk to you and answer any questions you may have. There prices are very competitive.

Good Luck, Paul

your 08 has the 10.5 sterling rear end if its a srw the last year of the 10.25 was 1997

yeah ya might get lucky setting up the new carrier.  Unless you have the right tools to measure it i would just go back with the old shims and run from there.  At least the shims and bearings are outbound so shim changes are quick.  what part of the country are you in?  the sterlings are alot easier to do with a diff spreader too