Never heard of EMD building a 645C, For the record EMD locomotives do not have a block, and beginning with the letter "A" each change of letter refers to a redesign of the fabricated crankcase. EMD built a significant number of locomotives with 567E diesels, these were SW1200s built for MP, T&P, SP, and SSW, after EMD had begun building road locomotives of the 40-series with 16V-645E3 diesels and the engine fabrication line had been converted from building "D" to "E" series Crankcases. It made no significant difference in the locomotives. BN and other railroads and rebuilders used the nomenclature of "645C" and "645D" to identify which type of power assemblies and what Crankcase type was in use in any particular diesel engine.Paul wrote:Just for the record, my GP-20 has a 645E and D-22 MG. Now, how many knew that EMD marketed a "645C", that being an "E" block manufactured with 567 packs? BTW, just slamming in 645 packs into a 567 does not change the engine rating or classification.
Union Pacific converted a large number of GP9s to a turbocharged version later referred to as an "Omaha GP20s" this work predated EMD's development of their own GP20, though the name may not have. See here
EMD Order numbers are stamped into the frame side sill on the Engineer's side right behind the step well, and diagonally opposite on the rear. This is the Order and Frame number, and not the serial until the middle of 1971 when EMD changed its serial number system. Locomotives built in Canada and a few oddball types lack these numbers until the 60-series were built.