Anyone know how to interpret the info stamped on AAM ring and pinion gears? I have an AAM 3.42 gear set for a GM 7.5/7.625” 10 bolt, and this is what is stamped on the gears:

Ring:
AAM 7.625” 12x41 (understand this)
029/1 MCA/4206 (what does this mean?)

Pinion:
AAM
12x41
029/4216 (what does this mean?)
MBB/2 (what does this mean?)

Also, there are no stamps or etchings on the pinion as to pinion depth/shims to use, and nothing on the ring to identify backlash needed. Start with .035 pinion depth? What about backlash?

Thanks!

 

12 x 41 = 3.42 (41/12 = 3.416666666....) That part is pretty straightforward.

The rest of them don't really mean anything that I know of, once they're outside of the factory. Certainly there's no info in them that has anything to do with installing them.

I have NEVER taken apart one of these rears and found ANYTHING BUT a .035" pinion depth shim; and NEVER set up one of these rears and had ANYTHING BUT a .035" shim after completion. So I'd say, start with that, and odds are VERY high you won't have to change it.