The cams from left to right, facing car, are 1, 2, 3 and 4. There are 2 numbers on each cam. Also there are 2 notches on each cam. To line the notches up to the backing plate you have to know which one to line up with. Cam #1 will have the number 1 and 2 on it, so you line up with the notch that is closest to the number 1, and so on. You need special service tool #6687 from OTC. It makes this job much, much easier.