I'm assembling a Bachmann H16-44 Baby Trainmaster and can't figure out what to do with a couple of parts. Perhaps these are used in some other model that gets the same parts bag.
The parts in question came packaged with the couplers. They are two domes, or hemispheres, or clear plastic about 3/16" diameter. I can't see any place on the model where they would go.
I might have thought these were headlights, except that the shell came with the typical headlight & number board assembly already installed.