nvrdone, have you considered using an assist piston with stock steering gear? These systems were installed on thousands of vehicles and they can give years of reliable service. The control valve replaces one end of the drag link and the assist piston attaches between the tie rod end and the frame like a steering dampener shock. This allows you to keep the stock geometry and the original steering column and box.
How hard would it be it would be to modify an old Mustang or Corvette system to fit an AD truck? It seems like these systems occasionally show up used on Ebay for a reasonable price.
