Abstract: An under frame tool bar attachment, for a light truck with a frame having a pair of generally parallel spaced apart frame side bars, includes an elongated tool bar, a pair of mounting assemblies, each adapted for securing the tool bar to a respective one of the frame side bars in transversely extended relation across the underside of the light truck frame and fasteners for securing the mounting assemblies to the truck frame and the tool bar to the mounting assemblies. The under frame mounted soil sampler includes an upright outer mast supported on the tool bar, a stabilizer for transversely stabilizing the upper end of the outer mast relative to the light truck box, a drill head vertically moveable on the outer mast, a power source for raising and lowering the drill head and a soil sampler tool removably carried on the drill head.