Eaton Detroit Truetrac Differential GM 10.5in 14 Bolt 30 Spline 4.10 & Down RatioThe Detroit Truetrac was the first helical gear differential ever introduced into the automotive aftermarket as an Eaton brand. It remains the leading helical gear type limited slip differential in the industry. Detroit Truetrac's 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. Proven design, low cost and