The Engine or Locomotive.
caboose
Maybe engine, since it is at the beginning of the train, while the caboose is at the end.
The caboose
The Caboose
It's a Caboose!
caboose
That is called a cupola.
Guard's Van or a caboose.
The plural of caboose is cabooses.
It used to be a caboose which was used by the trains crew.
It's a loose caboose
If tail is to rabbit, caboose is to train.