Motor mount lifts (MML) do any of two things:
- Correct driveline angles when lifted and not using a SYE. Tilting the motor up points the output shaft of the transfer case down lessening the angle between it and the driveshaft.
- Used along with a body lift (BL) to create room for tummy tucking the transfer case up into the body to gain more clearance of the stock skid.
Side effects of the MML is eliminating the need for relocating the fan shroud when doing a BL. If you do either a BL or a MML I'd recommend just doing both because of this.