If your car does not have rack and pinion steering, then it probably uses what's known as a frame-mounted gearbox, or simply steering box, as it is often called. As with most car parts, there will come a time that the gear box will need to be repaired or completely replaced. Installing or adjusting a car's power steering box can be a relatively easy or somewhat difficult task, depending on the amount of space there is in the engine compartment.
Step # 1 - Hydraulic Line
Make sure to put the brakes on and secure the car so that you can safely disconnect the battery. Once you're certain that the engine is cool, you can unfasten the tubing that pushes hydraulic fluid to the steering box. This is a somewhat messy task, but you'll be able to avoid it if you don't have power steering in your car. Put your drip pan beneath the steering box so that you can catch any fluid that comes out of the tubing. Using a line wrench, unfasten the hose screws. It may be a bit difficult to unscrew, as the fittings are usually put on very tightly, but a line wrench is much easier to use for the job than a traditional box wrench. Once the tubing is opened, be sure not to let any dust particles or other types of debris get into the opening in the steering box or tube.
Step #2 - Pitman Arm
Separate the steering link from the Pitman Arm using your tie-rod puller. To make this step easier, it's a good idea to use a penetrating oil to soak the splines in several days in advance. After removal, you will need to reinstall the Pitman Arm onto the new Pitman shaft and also torque it to comply with factory standards. Your steering box may have something called a key spline, which will only allow you to install the Pitman arm if it is positioned correctly. If your box does not have this feature, then you will need to count how many shaft turns as you go from lock to lock. You will then need to rotate the shaft half-way before you put the Pitman Arm in the correct center position.
Step #3 - Steering Shaft
Take the steering shaft apart from the steering box input shaft. Look for the bolts which hold together the frame to the steering box. Take off this part of the hardware, ensuring that the weight of the steering box is supported when you remove the last bolt. Pull down the unit and take it out of the underside of the car. If you are unable to remove it from this angle, then you will have to take it out via the engine area, in which case you will probably have to remove the power steering pump and/or the alternator until you are done. Install the new steering box and put the hosing, links and steering shaft back together, again torquing all of the hardware to the factory specifications. Put the correct fluid into the power steering reservoir and reconnect the battery. When you get the engine started, watch for any leaking of fluids and also turn the steering wheel from side to side. After each lock, turn the engine off and check the power steering pump for the proper fill level of the reservoir. Every few days after installing, be sure to check the level of fluids, as the air will be slowly escaping during that time.