[Johhny]

You were correct, they do interchange. I ran into a new problem tho:

I disassembled the old np203:



took out the input drive gear (32 spline):



and placed it in the new tcase:



Everything fits perfectly but I can't seem to reassemble the range box case...

There's a lever with shaft combined with a lockout shift that's located in the range box case itself:



The lever with shaft goes on 1, the lockout shift goes on 2:



I have no idea how to connected this when putting the case on, it al has to connect when the case is already half on, anyone has any suggestions?