Located in Ontario, CA. Performance Differential has been in business for over 7 years and is operated by Jim Cook. With over 15 years experience in Domestic Differential repair & upgrading, Performance Differential has established a very reputable name in the industry including the high performance world. Performance Differential builds about 750 rearends a year for customers in need of standard repairs, gear ratio changes and or positraction installations. Performance Differential also services the high performance world of ProStreet/Drag Race Cars, On&Off Road Trucks/4x4s, and the differentials in the SALEEN performance mustangs.Performance Differential has also been featured in many performance magazines such as Hot Rod, Ford High Performance, Chevy High Performance, Super Chevy, Super Ford, Mustang Illustrated, Truck'in and Mini Truck'in magazines. Jim Cook has been involved in Drag Racing and Off Road Racing for many years.