Those low houred, clean Series 3 machines are quite valuable, Series 3 machines were only made from 08-10, and of course the industry didn't move many machines in those years. Those drives were Rexroth if I remember correctly. They were decent, but all track machines of those years saw more failures than they do now. I am assuming it has a cab? If it does and only has minimal hours, for that kind of money (20K US?). Maybe even without a Enclosed cab, I would buy it in minute. If all he did was push snow, I would not be afraid of the drives, even if he didn't change the fluid. You could drain the fluid and mandate that its clean prior to the sale going through if your concerned about it. They only take about a quart of fluid per drive.
I am an H pattern guy (that is working on changing to ISO) but as long as your good with H, its not an issue. You may call a dealer and see if any of those pattern change components are still available if you must have ISO.
As I said above, they had a 4.5L engine that was used in the 590, it was just detuned for the 440, 450 and 465. It runs at a fraction of what its capable of. The limiting facture in a CTL is you may loose traction (because that is a medium sized machine) way before you ever lose power.
