I'm assuming here (a big ask I know, but bear with me) but I think that when the OP is referring to a "50/60Hz switchable file" he is referring to the electronics in the control side of the electrical generator part of the unit, not the engine.
See the illustration below. In the engine ECM (circled red) there is a flash file that controls fuel injection, timing, boost, and a whole host of other parameters.
From the C5L00792 Serial Number for the generator Stan has identified that the original Engine Arrangement for the genset in question was a 286-4916 (the S/N of that engine was FFH01045) and that there are significant differences between 286-4916 and 241-0020 including, but not limited to, pistons and turbocharger. I discovered that the fuel injectors are also different which is not surprising.
So my point is, what ECM does the replacement engine currently have installed..? The ECM from the original genset engine, or the ECM from the 241-0020 replacement engine..? If it is the ECM from the original genset then the performance of the engine will be adversely affected. It will run after a fashion, but the major differences in iron between the two engines means that it will never run right .........
Another piece of information. The original genset must have been a 50Hz generator, because engine S/N FFH01045 was dyno tested at 1500 RPM and produced 605 BHP.
In comparison engine S/N JRE07538 is rated at 475 BHP @ 2100 RPM.
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