It is the Bill of Material. Mostly used when ordering parts for the carrier stuff. I have messed with alot of axles, and never had to the number for getting parts. Most of the time it varifies what the axle is, year, make of truck, etc. Like I said, get a peice of sandpaper, clean up the axle tubes, can't exactly remember where it is on a rear 60, but possible on the pass side facing forward. They aren't very big, and sometimes they are barely stamped to begin with, so if it's rusted good, might not be able to read it at all. Should start with a 6, and be 6 digits long. Go do that, and post the numbers!!!!
