Here is a photo that shows the rod that attaches to the engine and sticks out through the end of the body. The rod shown is a piece of brass that I bent in the shape of an original, as this engine came without an original rod. The original rods are threaded to receive a nut on the end (see picture of rod sticking through engine).
Rod is shown on right side of photo, hanging.
Here is a photo of rod sticking through body of the red 3187
The rods stick through the hole on the upper left of the engine.
NWL