the np205 has been the gold standard for a long time because it is all gears--no chains----however the 241 is twice as strong as the 205--the dodge 241 is a driver drop---the chevy 241 is a passenger drop--i have heard you can adapt the chevy 241 for use behind a cummins automatic in a conversion--so it looks possible....as far as shift on the fly--whats wrong with just locking in your hubs and shifting the transfer case where you want it--on the fly---