Proven design, low cost and effective performance all make the Eaton Truetrac differentials the ideal choice for a wide variety of vehicle applications both on and off road. No maintenance - Just Traction. The Eaton Truetrac was the first helical gear differential ever introduced into the automotive aftermarket. It is based on technology derived from the Eaton Detroit Truetrac® limited-slip differential (LSD) which is a pioneer in helical gear based traction technology, and remains the leading helical gear-type limited slip diff in the industry. The Truetracs proven helical gear design eliminates the need for wearable parts, resulting in maintenance free traction recognized not only for its toughness, but its smooth and quiet operation as well. Vehicle Applications: Vehicle models with Ford 9" housing and 35 spline axles.