Of every motor type always exists a "L" (left) and a "R" (right) type. As you can see in the following picture, a left motor is always mounted on the right side bottom and on the left side top and a right motor is always mounted on the left side bottom and on the right side top. This fact is always based on the film direction which is marked in the picture with the green arrow. Generally it is not possible to exchange a left motor with a right motor and reverse. But if there are some requirements fulfilled, the change is possible. The case is detailed explained in point "9.5 Turn a motor