This job is rather unusual as the lower u-joint gives very little trouble. It is usually done when the car is apart and restored. This is the procedure for the replacement of the lower u-joint with the car all together.
1. The first step is to remove the allen screw that holds the u-joint shaft to the head of the steering rack. Procedure is the same for manual or power rack.
2. Inside the car, remove the two pinch bolts that attach the upper u-joint in place. The u-joint should now be able to come out of the car. You will have to slide the steering shaft towards the rear of the car slightly for clearance. On the Series 1.5 & 2 cars, the column will have to be unbolted as the inner shaft will not move in the column.
3. Inside the engine compartment, remove the bolt that goes through the accelerator pivot and remove the pedal half in the engine compartment along with the spacer.
4. Back inside the car, lower the pedal pivot. There are 4 bolts that hold the aluminum housing in place. Remove these.
5. Slide the shaft off of the end of the rack and then slide the shaft forward so it actually touches the radiator face.
6. Now you should be able to lift the aluminum accelerator housing and manipulate it off of the end of the shaft and off of the car.
7. The shaft should be able to now be brought through the hole in the firewall and removed through the interior of the car.
8. U-joint replacement is the same as the driveshaft u-joints. Reassembly is really the reverse procedure. There is a throttle return spring that needs to be manipulated into place and another persons help in sliding the accelerator pivot bolt through is also helpful. There is a 360 degree cut on the lower steering column so the alignment of the wheel can be changed rather easily.