5. To make sure the gears are meshing properly, they are painted with gear marking compound. Once the compound is applied the ring and pinion are rotated, the patterns won't always look exactly the same, but they will be close. There are many steps, tips, and tricks involved in installing a ring-and-pinion and locker. For the beginner this can be daunting. Always keep in mind that if you don't do it right, you've ruined a few hundred dollars' worth of parts. We highly recommend reading the Differentials Book by Randy Lyman. This is an excellent source of expert information.