A crane system for loading and unloading stone slabs comprising: a front support structure including: a pair of vertical legs each secured at a bottom end to the bed or wall of a vehicle; a front horizontal cross beam secured to a top end of the vertical legs; a back support structure including: a pair of vertical legs each secured at a bottom end to the bed or wall of a vehicle; a back horizontal cross beam secured to a top end of the vertical legs; a pair of bracing members secured to the vertical legs and to each other to aid in the stabilization of the system; a horizontal lift beam slideably secured to the front and back horizontal cross beams; a trolley assembly slidably secured to the horizontal lift beam; and a hoist mechanism secured to the trolley assembly.