Also look at the Prince web site. It has excellent diagrams and definitions of various hydraulic concepts.
I looked at Gearmore TNT. Appeared to be very well built, but I couldn't figure out how to install on my L35. It's recommended by my dealer.
It's also possible to do all of this yourself. Folks over at the hydraulics discussion group will help. But I think it's a long project if I would have tried to get it done myself.