These EMD locomotives share a common frame:
- SD38
- SD40
- SD45
These EMD locomotives
also share a common frame:
- SD38-2
- SD40-2
- SD45-2
These "Dash 2" versions have a 3 ft longer frame, but as
Triplex mentioned, the actual body isn't longer. This leaves extended platforms at the front and rear, and are what railfans typically use to identify the Dash 2 version. Another easy to spot feature is the SD38-2 has two roof mounted radiator fans, whereas the SD40-2 has three.
The SD40M-2 rebuilds were (again as
Triplex mentioned) usually either the SD40 or SD45. To complicate things, Southern Pacific used the SD45 with an SD40 rear carbody for some of their SD40M-2 rebuilds.