This is a coupled 2 degree of freedom model.  It is a suspension model of the truck.
 

The model can translate and rotate.  The differential equations (ODEs) are

Using values for the system parameters the following explicit equations will be solved

This is a fourth order, linear, constant coefficient, coupled  , nonhomogenous ordinary differential equation

The symbolic solution was not obtained.  Only the numerical solution is shown.  Also shown is the animation of the truck mass