Peterbilt Motors Co. has earned the top spot in J.D. Power and Associates’ 2001 Customer Satisfaction Study for conventional-style medium-duty trucks.The study is based on interviews with more than 2,000 owners of two-year-old medium-duty trucks. The study analyzes customer satisfaction in five main areas: vehicle performance, vehicle downtime, drivetrain, design and styling, and warranty, said J.D. Power. Peterbilt, a division of truck builder Paccar, is based in Denton, TX, and has come out on top in J.D. Power’s study twice in the last three years with its Model 330 Class 6 and 7 truck chassis, originally introduced to the commercial market in 1994.