On the motor end of the power window unit I have checked how I want the motor to sit then checked where it would be possible to mount the brackets (on the motor end and the door skin). Then I have mounted two brackets to the unit similar to how they are mounted on the gear end.

Note: on both ends of the unit do not over tighten the small screws, a screw driver gives you a lot of leverage and it is possible to shear the screws off if you are not careful.