I did a study of seat belts years ago when I installed them on TF. Our trucks don't have a good place/structure for them. Sheet metal walls and floors, even with backing plates, are not optimum but it's all we have. The Fed Spec is about 9000 LB strength for hardware and the anchor area must withstand that, without tearing loose. A person weighing 160 lbs at 30 MPH can create about 30g force which is almost 5000 lbs! The average 95th percentile male is 215 lbs. That is about 6400 lbs force at 30 MPH.
The shoulder bolt placement is sort of important to get right per instructions. Otherwise you either choke or upper body not held. A low strength shoulder mount structure can break thru and hit you in the head and........
It is true about the steering wheel/shaft being dangerous. Aftermarket columns sometimes have collapsible features. Also when there is a universal joint with a change in direction of column shaft to steering box, that can prevent getting shafted.
The car and truck manufacturers finally realized that the seats being held were as important as the belt. Seat bolts were shearing off or busting thru seat brackets. Seat moves forward but you are held back. Bad news, So they redesigned seat mounting structure. Sorry to say we have that potential issue on our trucks.
Similarly, of course, you never attach belts to the seat frame.
There are few statistics on old trucks, re: belts, that I could find. Our accident rate is low. We drive better and we usually don't speed.
All in all, it's better to have them if done with some thought. The aftermarket belts and hardware meet the backing plate sq. in, thickness of washers, size of threads, materials and web strength required by the Feds. It's our truck's structure and design that is not up to par for seat belts.
