What are you trying to do, are you retrofitting rear electric windows? And what do you mean with the window regulator? The electric motor and arm that moves the window up and down?
In that case (if I remember correctly) the motor is at the rear of the door and the arm is at the front. The motor/mechanism should have an L or R stamped on it to indicate for which door it is. I remember having difficulties finding the correct holes for the rivets when I retrofitted mine, but all holes are definately there.