In this research, ride quality of a multi-degree of freedom 3-axle rigid truck is investigated to understand its vibration specifications. The truck is a Benz 2624 model. The system is considered for an off-road duty. Current research concentrates on the modeling and simulating the truck. The linear model indicates cab and seat suspensions, rigid live axles, and suspension geometries. The Lagrange?s equation is used to obtain the motion equations and system matrices, and the numerical central difference method is utilized to obtain the system responses subject to sinusoidal road excitations. Since physical parameters of the vehicle were not available, the truck is modeled in Solidworks CAD software to obtain the dynamic properties of its components. Then, a code is developed in MATLAB to calculate system time responses under different cases for the truck moving in high speed. The developed model can also be used in newer truck with some modifications. It is also necessary to have accurate information for input data in order to change the current model.