I am installing a dual transfer case setup and have a TH400 with NP205 mated to it. I plan to install a NP203 range box on this tranny. What is involved in mating a NP203 TH400 version to a TH400 that was originally equipped with a NP205? I read Watson's site and feel I understand, but just cant fathom why GM would offer two different versions of the TH400 for 4x4 Applications. Has anybody modified a TH400 originally equipped with an NP205 to accept an NP203? I realize I would have to drill and tap the face of the NP203 if I go this route. What about clocking the NP203 range box totally upside down for clearance, do I just drill the bolt pattern in how it will be clocked? Thanks in advance.