There's one of each. The Pitman arm attaches to the steering box. The Idler arm is on the other side of the steering shaft. You can go to Autozone website and pull up the parts to get an idea of what you're looking at. As for difficulty...it's not the easiest job, but you can do it. It really depends on your ability and tools. The only problem I really had was having to re-adjust the steering tension when I was done. The steering wheel didn't want to go to center by itself. There's a little bolt with a locking allen screw in it on the steering box I had to loosen (or adjust). Also, if you do it, keep everything in place when you swap them out. Don't move the steering wheel or anything.