Swapping the idler arm for the d21 steering box provides many advantages in the terms of strength and durability. The steering box is sealed with a oil bath, meanwhile the Idler arm is exposed and needs frequent greasing. The steering box is easily twice as strong both in weight and in design. Running a steering box avoids the need for a idler arm brace or costly bronze bushings. Parts list: 1990-1986.5 D21 Manual steering box. This item is typically found on Regular cab 2wd short box Hardboby pickup trucks. It needs to be this specific year range as all boxes newer than 1990 have a larger spline. The larger spline spaces the box 10mm further out than the current idler arm so it's not recommended. Using another Xterra box for example would offset the idler pivot 10mm further way from the frame. I'm unsure of the effects of such a swap. The 1990-1986.5 box power steering or manual is a replica of the Xterra idler arms geometry. 1989-1986.5 D21 Pitman arm. This part needs to be off of a 4wd Hardbody or any Pathfinder with power steering. The arm for the 2wd manual box is shorter in length and will not work. Steering box bolts. When you pull the box save the bolts. Tools: Hack saw or Sawzall Welder or JB weld Sockets and wrench to take fasteners off I think 19mm and 27mm Start with your steering box. Put it in a vice and use a pipe wrench to remove the lock ring. Use a punch and hammer to rotate the cover out. Inside you will find a worm drive and bearing. Lift all items out and discard. Then you can begin the reassembly. You have to plug the hole left in the box now that the shaft is gone. I removed the rubber seal dropped a fender washer in and filled it with welds. You could likely use JbWeld or other sealant. The box itself is not under pressure and the oil level is below the hole. Alternatively you could probably remove the rack gear by taking the balls out of the cages on the back and reinstalling just the worm shaft. Just make sure its not left open. After reassembling the box. Note the bolt holes. The two lowers are on the same plane while the two upper holes are at a slant angle. To mount this left side steering box on the right side, modifications to the mounts must be done to reverse the angle. Using a hack saw or sawzall you can slot the holes as shown to bolt up. Ready to install.