Need all info I can get on alco switch engines
Brue it's a very large topic you're asking about. See https://en.wikipedia.org/wiki/List_of_ALCO_diesel_locomotives and try and narrow it down a bit. There were many different Alco switchers built with inline 6 cylinder engines.
Alco switch engines built with inline six cylinder engines date from February 1924 to January 1969. The earliest boxcab switchers had Ingersoll-Rand engines, GE electric gear, and Alco built everything else. Starting in 1926 Alco experimented with McIntosh and Seymour diesel engines in its switchers. Alco ended up purchasing M & S in 1929 with its established diesel engine plant at Auburn, NY it was a natural to work with Schenectady based Alco.