I am selling a Voltmaster 15kW 540 RPM PTO generator. I bought it new in December 2007 from Generators direct and paid $1300 for the genset (without PTO shaft or cart).
I built the cart in my shop; I am an experienced welder/fabricator and the cart is high quality. It has casters on it so that the generator can be disconnected from your tractor and easily wheeled to a storage location. It is set up for category 1 three point, but works fine with bushings for cat 2.
PTO shaft is included. It is a 1-3/8" six spline; series 4 (rated for 35-55HP). This is larger than needed, but provides for increased durability and reliability. I purchased it new when I purchased the generator.
The generator requires 24 PTO HP for full rated output (but will work fine with lower HP, just won't be able to pull 15kW from it). I ran it behind my kubota B3030 for an hour or two, and it had no problem even under full load and large starting surges.
This generator has been used for a total of about 3 hours; other than those few hours, it has been stored inside of my heated and dehumidified shop. It is in almost new condition. I am only selling it because I now have a permanently installed 3 phase diesel generator for backup power; it suits my needs better than the PTO set did.
I can plug this set into my shop and demonstrate it running under full load, measure individual line currents, show voltage waveforms, etc.

Here is a video of the generator being tested under load and some additional pictures:
Demonstrating my PTO generator behind a Kubota MX5100HST - YouTube

Here is a link to the place where this was purchased:
Voltmaster PTO15/12 PTO Generator - PTO15/12 - 12 kW Tractor-Driven PTO Generator (540 RPM)

Price is $1100 cash.

This is located in Seaside, OR but I make it into Portland every few weeks and I could bring it with me if needed. I also make it down toward Dallas, OR once every month or two, and will be driving to Redding, CA over Thanksgiving and can always throw the set in the bed of my truck during any of those trips.

Feel free to PM me or give me a call with any questions. Thanks!