What does a motor mount lift do?
A motor mount lift is designed to improve driveline angles. By lifting the motor up you tilt the transfer case down towards the axle. When installing a lift kit you can do a motor mount lift instead of a transfer case drop. Eliminating the transfer case drop will give you more ground clearance. Some also do a motor mount lift when installing a 1" body lift, because the body goes up one inch, the motor goes up one inch, no need to relocate the radiator.