[406 Q-ship]

I would just put in a regular 3 point retractable belts from somewhere like Julieanos. To mount racing harnesses, you need to build a harness bar (like the roll bar) inside the cab of the truck. I guess you could reinforce the sheet metal of the back of the cab, then mount the shoulder belts to it rather than a harness bar. You can NOT run the shoulder belt to the floor of the cab, the angle will be incorrect and will cause a spinal injury if your son was involved in a inncident. Go to one the websites like Simpson and look at the angle of how the shoulder harnes has to be installed to not cause more damage to the wearer. Plus the sheet metal is NOT strong enough to hold the belt mounting without some kind of reinforcement. There is more science to seltbelts than most understand.