Dwayne; Here's the Cliff Notes version;
Obviously, remove the body shell first.
If you have the horizontal motor version, two screws go through the motor casting up near the spur gear drive system; remove these and the motor lifts off the truck and the truck drops down off the pivot post on the frame. Beware the power wire from the rollers is still attached to the diesel.
If you have the vertical motor drive version, a screw comes up from the bottom of the truck and screws into the "nose" of the motor itself to release it.