Eaton
Eaton offers a posi unit and a locker for the 8.8 that easily replaces the stock piece. The Eaton posi has carbon disc clutch packs preloaded by a central spring assembly located behind each side gear. When torque increases, so does the clamping load on the clutch pack. The Eaton locker operates in a different way than most limited-slip units. It is speed sensitive in that it has a flyweight governor that responds to changes in wheel speed. When one wheel speeds up, the governor flies open, pushing the flyweight onto a latching bracket. This bracket then starts the lock-up of the unit, allowing power to be transferred away from the slipping wheel. The process is pretty trick. Contact Eaton for details and pricing.
Ford Racing Performance Parts
FRPP offers a host of parts for the 8.8-which is made by Ford-so you know they'll fit and work without a problem. One of the items that caught our attention was the 8.8 ring-and-pinion gearset. The gears will fit the stock housing, and there are many different ratios from which to choose, depending on vehicle weight, horsepower, and application. The gears will empty your wallet $225, but they are a great way to spend a little cash to go a bit faster. If building a rear isn't your strong suit, then take a look at FRPP's 28-tooth Traction-Lok rear axle assembly. The assembly is nearly 35 percent stronger than the 7.5-inch assembly, and is fully assembled with the housing, gearset, and 28-tooth posi unit. The unit will fit in any Fox-body, comes with a choice of 3.55 or 3.73 gears, and will set you back $875. If a new S197 sits in your driveway, feel free to call FRPP and pick up the newly released rearend girdle for the '05-and-up Stangs.
Also, when it comes to differentials, check out Ford's Traction-Lok, which features plate-type clutches, meaning power is moved around through clutch-pack bias. As you lose traction, the clutches bind tighter together, transferring power away from the slipping wheel. Call FRPP for applications and pricing.
Holcomb Motorsports
For ultimate protection and durability, pick up the appropriate amount of Royal Purple Synthetic gear oil from Holcomb Motorsports. Priced at $8.99 a quart, the 75W90 gear oil will last a long time, no matter what the circumstances.