RE: From NV56 to G56?
I doubt you would ever 'break' an NV5600. . .I could see it from misuse, hot shifting, and incorrect fluid. keep good 5w30MTF in her, use the clutch when you shift and you wont have any problems.
besides, the G56 is a little shorter than the NV5600, so a new drive shaft or two would be needed.