Marty: In photo #2 you can see an arm/bracket on the smoke unit that has a U shaped opening. Further along that plastic piece toward the smoke chamber is a shoulder molded into the plastic. If you set that smoke unit up against the motor frame and align the U shape with the hole in the frame, you will be able to screw a screw over the red U shaped plastic into the frame holding the smoke unit in place. The smoke bellows/flapper in already mounted onto the motor frame and should move freely when it is pushed as if with the crosshead. Once the unit is mounted into the boiler body and secured with the crosshead/front truck steamchest bracket, it should work okay. Hope this helps. Dennis M.