I just purchased a workshop manual on a website for the Kawasaki FB460V engine. However, the cover page is for the 10400V engine. The specification page states it is the FB460V, and the electrical system does also, otherwise there is no mention of the engine model in the text or diagrams. I can't find much on the 10400V in a Google search, and nothing about it searching this site.
Like a lot of stuff you buy on line that manual was most likely stolen,
So the 10400V applies to the equipment that the engine was originally fitted to or the internal stock number for that publication.
AFAIK all Kawakasi stationary engines have numbers that start with F
