I don't see a price, but it looks interesting. They talk about running it off a PTO, but then they say it's mounted underhood on that Ford so I don't know which way it operates. Belt driven would obviously be better for the bus application as I have yet to see a bus with a power take off though the Allison's do have the provisions for them. With that gennie, a 3:1 ratio would be ideal I think. You'd have to go over 3333 RPMs to overspeed it while a 1000 rpm high idle would give you the 3000 rpm at the gennie required.
Northern Tool sells a similar output gennie head that might work in the same application for $400 http://www.northerntool.com/webapp/w...6970_9040_9040
I don't see any minimum or maximum speeds listed though which could come into play. It also wouldn't include a clutch to disengage it. While an AC compressor type pulley clutch would work great on it, I'm not sure how well you could adapt it to this use. It is worth looking into though given the price. Perhaps a call to Northern could answer the questions as to feasibility of one of those gennie heads under hood.