I have read all the responses on this thread and many others concerning belts in a AD truck. My thinking and it is probably very flawed, so I expect to get flamed is a shoulder belt will not help much on frontal hit impacts with any speed involved, I think no matter what, that steel post of a column is going to get you. I'd rather have a lap belt and lay down. I have personally seen a guy thrown out of a vehicle and survived that would of obviously not if he had a three point. But alas, one could argue the merits and demerits of restraint systems forever. I think a successful lap and shoulder restraint includes a breakaway column and air bag. I think history has shown the evolution of these safety devices over the years and it has definitely evolved with all components and crumple zone sheet metal working in unison. One is not much good without the other IMHO, so mine will have lap belts only with hope of stopping you from getting thrown around too bad and sustaining life for a under 25mph hit, after that seems that everything else is a crap shoot.

1953 Chevrolet 3100
261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY Gallery
Video of the 261 running

1964 GMC 1000
305 Big Block V6, sm420, the next cab off restoration