I've got a '62, and added aftermarket lap belts. Won't do much to keep anyone out of the dash or steering wheel, but it'll keep everyone in the truck in case of a bad accident.
I'm planning on 3-point shoulder belts in the future, but they're a lot more involved to install.
I don't think I'll be able to easily add 3-points to the rear, unless I beef up the entire seat frame and make them an integral part of the seat structure, like on new vehicles.
-Brad
