Rattling noise is one of the most significant noises pertinent to manual gearboxes. The paper deals with modeling and numerical analysis of commercial powertrains. Multi-body modeling is adopted to investigate gear rattle phenomenon in several engine operating conditions. The linear and nonlinear models include: crankshaft with pistons and flywheel, friction clutch, primary and secondary shafts with their corresponding gears pinion, differential crown wheel, axle shaft, tires and vehicle body. In order to analyze the gear rattle, the numerical analysis is made with respect to teeth relative displacement, teeth contact force and index β.