T-case education

Can anyone help educate me. What the difference between the NV242 , 249, and 247 transfer cases and is NP the same as NV with transfer cases? if so according to the mopar chart that NAGCA lists, made by chrysler ( there is a link to it on the bottom of thier grand tech page) as of 2000 all jeep t-cases are supposed to take ATF + 3 including the 231. Is that really so ?

NP = New Process

NV= New Venture

New Process became New Venture...

You can find all sorts of info about them by just typing "NV249" ect in yahoo or google. THey each use different methods to split torque between front and rear axles.