Originally Posted by
bacicat
The X5 5 speed and later 6 speed manual will fit behind the M57 engine and the RR Transfer case will bolt up without too much issue from what I can find out. The gearbox in the X5 is a good unit and works well, although it was never as popular as the auto, and is quite rare in Australia.
Not sue how the terrain response and hill decent would work with it (if at all) but reliability wise it would be fine as it's rated to take almost twice the torque as the 5L40E. Might even be able to chip the engine without fear of a catastrophe happening. :D
There are plenty of other hurdles though - clutch, exhaust (RR exhaust will foul the clutch fork), gearshift, mounts, drive shafts and electronics. Still, I think it is doable... Maybe one day I'll have a crack at it.