can I swap in the trans from my 01 to my 03 cummins 4x4?
The 01 is a built unit with the upgraded newer valve body.

 

You can but will have to mill out the neutral safety switch hole for the range sensor setup on the 3rd gens, drill a couple holes for the mounting screws, and change a few internal parts that actuate the range controller. Its chamfered hole that is larger than the older neutral safety switch.

 

Thanks I may just take it to jeff.