rails are interconnected by longitudinal rails 53 and 54 which are located at respective ends of the rails 51 and 52 the rails 53 and 54 thus extend from one end at the rail 51 rearwardly to a rearward portion 55 located beyond the rail 52 the rearward portion 55 of each of the rails 53 and 54 carries an end plate 56 which stands in a vertical plane at right angles to the rail and mounts to a front face of the rear bumper 13 b as shown in fig2 thus the bumper is attached to the cradle rather than to the longitudinal beams 34 and 35 constituting the main frame of the vehicle the bumper can be attached to the cradle when the cradle is separate from the vehicle frame so that the bumper forms part of the components carried by the dolly the rails 53 and 54 are generally l shaped so as to form a horizontal flange 57 and a vertical flange 58 at one side of the horizontal flange the vertical flange is as shown in fig3 on the lefthand side of the horizontal flange for both of the rails when viewed in rear elevation the horizontal flange when the cradle is installed in the vehicle sits on top of the upper surface of the rectangular beam 34 35 with the vertical flange 58 along the lefthand side of the respective beam 34 35 in this way the cradle on the dolly can be rolled into the area of the engine compartment with the dolly to the left of its final position so that the vertical flanges 58.