Good information on the tires, HÃ¥kan. Actually, I think AMT missed a "6" in their description. According to the Diamond-REO brochures that I have access to, the Model Number brakes down like this: C - Conventional 116 - 116" BBC 6 - Six wheels (each rear dual set counts a one wheel) 4 - four drive wheels D - Diesel F - front axle forward L - Lightweight (highway) So, an off-highway tri-drive with the same cab would be C-11686D-OH.