square, triaxial vehicle with the rear of a g…!?

I recently met a very memorable vehicle on the bike: a box-shaped vehicle with two rear axles, which stood relatively far apart and the rear of a mercedes g. does anyone know it? I can only see it from the side and from the back, but I would be interested in technology and a few pictures, also the area of use and whether it is a original civilian vehicle. thank you! dear gruss oli