[Trouble Maker]

Correct. I believe it's derived from the Jeep Quadra-trac system, or is the same in itself. 01+ has no 2wd, only AWD/4x4HI/4x4LOW.

No, it was the same as the Jeep Selectrac NP242 system.

The Quadratrac systems used either a viscous coupling(NP249) or Gerotor clutch packs(NV247) to to bias the torque frt/rr.

 

[Trouble Maker]

I know I would get better fuel milage and have some fun buring out.

No real difference in mileage between AWD or part time 4WD since the front gears are turning all the time anyway.

 

[Trouble Maker]

4.

Awd uses essentially a clutch/torque converter that can slip itself between front and rear axles so it can be in effect all the time.

Not the AWD system used in the Dakota/Durango. It is basically an open differential that allows for front/rear speed differences but it can be locked to split the power equally to the front and rear.