Chevy up through 64, Ford Mustang up through 70, and Corvette up to 80 or so used the assist cylinder. The drag link has the control valve in it and all the fabrication that is needed is one bracket on the frame for one end of the cylinder and another on the tie rod for the other end. They work well and feel good but not the best for a lowered truck since they have hoses running between them that have to have slack to allow lock to lock turning. You don't touch the factory steering box and the drag link with the control valve is a direct bolt in replacement for the non-p/s one so the steering geometry stays exactly the same. I have a 64 Chevy chassis with the body off if you need a picture of the factory p/s set up.
