I have a 1995 Ram 5.9 Cumming 12 valve auto 2 wheel drive. I want to put that Cummins engine into a 2001 ram 2500 auto 4x4 will it fit ?

Yes you can and it's not nearly the head ace as one would think a 46re trans will bolt up to a 5.9 only suggestion get a different torque converter made for pulling cause the factory one for that gas burner won't hold up and draining the gas is the other hard thing but as long as you get most of it out of the tank like no more than a gallon left and you fill the tank up with diesel it won't hurt it at all but make for dam sure you get all the gas out of the lines going to the motor cause that little bit of straight gas will screw up your world