Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
American diesel locomotive
ALCO RS-27
Minnesota Commercial Railway 318 at Minneapolis, July 2009
The ALCO RS-27 (specification DL-640) was a diesel-electric locomotive built by ALCO between December 1959 and October 1962.
Only 27 examples were manufactured. With ALCO's introduction of the Century Series line in 1963, the C-424 (specification DL-640A) replaced the RS-27 in the builder's catalog. Today, the Minnesota Commercial Railway has the only two RS-27s left in existence; however both have been placed into storage.