OK. Thanks all... This is great.
I have seen the Dana PDF, which gives some good adjusting/rebuild info, but I am looking for some really basic stuff to start with, like the difference between the 201 and the 221, load ratings, etc.
Possibly the intro to the overhaul man. or the specs section might have something?

Also, how were the "early" axle models different from the late model axles? Is one preferable over the other? Were there design improvements?