bars 54 fig1 and 2 the coupling assembly further includes a cable cinching mechanism 56 which in turn is coupled for example by an eye bolt 65 fig2 to transverse frame beams 36 securement of the frame to vehicle 29 can easily be accomplished by positioning transverse coupling bars 54 underneath the cargo bay of the vehicle the cinching mechanism 56 can then be used to pull the bars up firmly against the underneath frame structure of the vehicle so that the bars 54 and cable assemblies 52 cause the frame to be clamped to the bed or cargo bay of the vehicle this clamping action couples the frame of the crane assembly to the frame of the vehicle so that the entire weight of the vehicle can be used as ballast and a counterbalance to weight lifted by the crane in a manner which will be described more fully hereinafter the improved crane assembly of the present invention further includes support means generally designated 61 carried by frame 22 and formed for movement into and out of engagement with a support surface 62 usually the ground on which the vehicle is supported support means 61 is formed to stabilize the crane assembly as mounted in the vehicle this is preferably accomplished by providing transversely extending arms 63 which are pivoted at 64 about a vertical axis to frame beams 36 and which carry.