I believe the 5 speed automatic on all 5.4 liter E31's is a steptronic type. This would really be an upgrade over the earlier 4 speed auto, but would probably be very expensive unless you could find all the parts at a salvage yard. Even then it might not be technically possible. Any experts out there know if it is possible to put a newer srteptronic transmission on an older (5.0 liter) engine?