When I first started to look into lockers back in 2003, I started reading more about differentials and the proper maintenance in prolonging the life of gears. I’m a maintenance freak, so I tend to pay close attention to the specifics. Anyway, I did a quick Google search and immediately turned up this thread:

“Now that you are ready to finally put the diff cover back on there is one thing you need to do. Detroit lockers tend to deposit small metal shavings in your gear oil, which is not the best mixture. To keep the metal shavings under control it is recommended that you glue a little magnet to the inside of the diff cover. This way all the free shavings will eventually get stuck to the magnet, which will keep you oil brownish, not silver in colour. With the magnet glued in with some RTV, put a bead around the diff cover going both on the inside and outside of the bolt holes. After this all that needs to be done is bolt on the cover, torque down the bolts and fill it with oil.” http://www.bc4x4.com/tech/2002/lockerinstall/