do you have a hand held contactless tach yet??
you need one to look at the rpm on the diesel part...
put the reflective tape on the crank balancer.
cool these days as they are cheap!!
last I knew these were " fixed rpm" to get the hz.
they are adjustiable and have a electrical to mechanical governor to keep the rpm steady for the load changes.
but the hz needs to be right about center of the 60hz...
last I knew unless you are setup for 208 on your L1 to L2 load you need an accy transformer to change that to
single phase L1 125 vac to neutral L2 125 vac to neutral and L1 to L2 as 240 vac...
maybe something like this https://store.maddoxtransformer.com/...nt=45588273993
but on most late trailer units I have worked with they also have different taps for output
and shorting bars to "program" or "select" the gensets outputs.
are there any printed paper tags inside the side covers?
the tag on the generator alternator or "head" is just for that unit..
but some times unless the head has been swapped out you can track that back to the gensets model and serial number with a call to the mfg.
on the older stuff it is all "hand check"
now days after 2006 mfg most of it is all in a data base some where...
unless the mfg had folks enter the data for each model and serial number if they were all option units during production.
back then most of the larger units were just that!!
made to the clients specs on demand...
yea we need to know more on the head wiring...
I suspect it is a 208 Y 3 phase style..
but it could have the correct taps for 240.