Like the Amazon descriptions indicate, this is for '90s generators. But, at least down here since we get stuff fairly late in the distribution process, it also covers '00s units. I have a Porter-Cable Model BSI525 5.25 kW (6.5 surge) generator that required engine service and I had a dickens of a time getting the generator rotor off the engine output shaft, in order to disassemble the bottom end of the engine; it is a tapered fit and one must use a big two-jaw gear puller to get it off. And I've had various other maintenance tasks; hence, I figured it was time to get some written instruction. This book covers my needs just fine.
Included are instructions, line drawings, and wiring diagrams. But note that the engines are NOT covered; you must purchase the appropriate engine manual for that. It starts off with a chapter on generator fundamentals, which is nice if you know nothing about how generators work. But the book assumes you know your way around machinery and have some familiarity with tools. After all, it IS a Clymer "ProSeries" book.
One erroneous product description detail should be noted: the Amazon info says this book covers generators up to 13 kW, but the back cover of the book says it's only good up thru 8 kW. I haven't personally verified the numbers one way or the other.