steering gearbox problem

I was wondering if anyone has any ideas on how to fix my steering gearbox issue. It started when I took my 70 Dart to a shop for some front end work. They replaced my power steering gearbox because the seals were leaking with a reman. unit. The steering was terrible after that. They replaced that one with another one, it was just as bad so I just gave up with the shop. We've tried to adjust the 3/16 nut on the unit to tighten it up, adjusted the steering column at the dash, still no help. There's ton's of play in the wheel even when the car is off before the pitman arm will begin to move. The car wandders all over the road. All other front end parts are solid.

So this past weekend some friends of mine put another gearbox on for me. Same problem. Is it possible that all these reman. gearboxes could be bad? Doesn't seem possible. Any help would be greatly appreciated.

Thanks! Steve