Slanted Offset-Cupola Caboose - Ready to Run -- Grand Trunk Western #122 (red, black; Noodle GT Logo)STREAMLINED CABOOSE WITH OFFSET CUPOLA GRAND TRUNK #122 HO Scale. The original design of the Streamlined (sometimes called Offset) Caboose was built by the Wabash Railroad in the early 1950s. The most common form was a small windowed projection on the roof, called the cupola. The crew sat in elevated seats to inspect the train from this perch while the train was moving. The caboose also provided the train crew with a shelter at the rear of the train.