materials characterized by high strength corrosion resistance and durability although not illustrated the structure of the sections 12 and 14 may be suitably reinforced by integral strengthening channels ribs and the like if desired but in the present embodiment structural rigidity is provided by filling unused internal spaces with suitable plastic foam material as seen in fig2 the forward section 12 includes a pair of laterally spaced apart side walls 22 and a front wall 24 as best seen in fig4 the central portion of the wall 24 is formed to define a forwardly open generally rectangular recess or receptacle 26 the rearward extremity of the receptacle 26 is joined to and opens into the forward end of a longitudinally extending cylinder 28 which is supported at its rearward extremity by a rear wall 30 of the forward section 12 an elongated towing bar or tongue 32 of tubular cross section and mounting the usual towing fitting 34 for connection to a vehicle mounted towing hitch not shown is carried within the receptacle 26 more particularly the rearward extremity of the tongue 32 includes an integral vertically oriented transverse bushing 36 adapted to receive the shank of a locking member 38 the shank normally projects through the bushing 36 and also through cap nuts 40 and 42 which are fixed to the upper and lower surfaces of the cylinder 28 one extremity of the shank is.