The WalthersMainline Phase II High-Hood GP9 is a must-have model for your first-generation diesel roster! Outwardly similar to the earlier GP7, and sharing the same boxy, no frills body with its high, short hood, minor production changes in the number and placement of louvers on locomotives built from 1955 to 1957 resulted in what modelers and railfans refer to as "phase two" GP9s.