For OEM differentials from the 2004-2009 Dodge Durango 42RLE 4 Speed Transmissions.Traction Concepts Limited Slip Conversion Kit installs into your non-LSD open differential, converting it into a proven and competitive limited slip differential that enhances your traction needs. Our TC Limited Slip 1.5 way LSD will considerably improve handling in daily driven, street/strip warriors, or a full race vehicle. All Traction Concepts products are constructed of only the highest-quality hand selected materials. With over 500,000 miles of vigorous professional performance testing (SCCA, drag, rally, hill climb, ice, rain, etc.), we have been able to fine tune each application through specific heat treating and Rockwell testing to achieve maximum performance and reliability. Each Traction Concepts LSD Kit is assembled with pressure tested matched sets of progressive-rate springs to achieve equal load distribution to the disc plates, which dramatically enhances reliability and performance. With such a passion for perfection, Traction Concepts is confident that when you choose our TC Limited Slip Conversion Kit, you are choosing, by far, the best limited slip conversion kit on the market.