George, Atkins is now using the Powersport internal ring gear psru. You can check it out on the web at
www.powersportaviation.com . It's a really nice unit though heavy, around 60 pounds. I do like the arrangement in some ways. But it is high priced at $6,500.00! If I spend this much on a PSRU I would buy the Mistral. Lighter and configured for a hydraulic constant speed from the start. I had been in communication with the designer of the PowerSport unit for some time. He was supposed to be building a new unit that would handle more power and be lighter. He was involved in auto work though and hasn't made much progress in over a year. The one big advantage of the internal ring gear unit is that it offsets the e-shaft centerlind about 3 inches lower. That lower e-shaft center line makes it much easier to wrap the intake over the engine. PowerSport has had some money problems so I don't know what the current status of the company is. If I was to order from them I would probably request a escrow account to prevent getting into trouble.