Neil: May be sidewinder can help on the pump question, but what I have found in the service manual for an 8780 1997 and 98, it list the rotor pump and motor as Sundstrand 90 series 100cc same as on the 8570. The propulsion on the 8780 us the 90 series 100cc pump pig back together, the 8570 use a 40 series pump. I did get to look at a challenger 670 and it has 2 90 series pumps pig backed together a 100cc and 50cc and the pump is a 130cc. last year cutting safflower the crop was very dry so we was running the rotor very slow 110 RPM and the monitor kept drop to 000 RPM but the rotor was still going I decide that it would not read that slow, so I wonted to change to the newer pickup wheel with60 niceties, and when turning off the separator and back on the rotor speed would not be the same (I did not like that) the old rotor control is a very simple design and has part when used for a few year would get dirty and worn to be not vary acuter, so I wonted The constant speed control, it is made by Sauer-Danfoss-Sundstand the same company that makes pump and motor. http:__www.sauer-danfoss.com_ It look like there are two way to put on a 8570 first the way I am work on now or to put anther pickup wheel in front of the one that is there and mount the hull effect sender above, run it only to the rotor control. In my researcher I found that Micro-Trak and Dickey-John both have ad on speed monitors that could be put on. With in a week or 2 I should have enough time to finish getting the monitor right. Thanks Dee