Fwd Repair System

Please be kind, as I'm extremely new to 3D CAD, and this is rather crude, but I needed a US Army Forward Repair System in HO-scale for my planned HO-scale model railroad. This is the latest iteration, designed in Sketchup, a Forward Repair System opened up for use. Also, bear in mind, there should also be a generator, an air compressor/air tank, and Oxy-Acetyline cylinders in the open end, and a folding hydraulic crane on the other end. I used models that I downloaded from various places, and scaled them down to fit (and look decent). Please feel free to update/improve/etc.