I thought that "all" 19HP versions had power steering? and that it was optional on the other "GT" series (but not the older "S" series which is basically the same tractor)
and no I am not just saying that because my 19 HP has it either
When I was looking around to see what these machines were, between the time that I decided to get my machine and the time that it got here, that's when I saw what I did to make me think that it was on all the 19's
Mine has a KT19 "series II" which is supposed to be improved over the Series I but since I haven't had either series of KT engine apart before, I don't know the difference, just that they are both Kohler opposed-twins.
On the power steering; I have not yet had a chance to actually use my GT19, I did find out one thing that sucks about this PS system; there is no mechanical linkage between the steering column and the front wheels, just a fluid connection; I would like to find either a Magnum 18 or magnum 20 to replace it "when the time comes"
if you have to move one equipped with P/S other than in whatever direction the wheels were pointed the last time it was shut off the only way to do so is to put either a jack or a dolly under one end.....
There's a nice Briggs 18 hp IC engine in new condition on eBay for less than $500 right now... The same basic model as what I'm putting in mine. (unless the diesel will fit).
And, I know what you mean about the power steering with the orbital valve, although some will actually act as a pump even if the engine is off if you spin the steering wheel the direction you want to go.
I have that type of system on a Toro mower, and I'm tempted to put it on this machine. I also have a power assist system off a JD 400--this one keeps the mechanical linkage, but has a valve that piggy-backs on the drag link, and a cylinder from the tie rod to the frame. Doesn't work too bad, I understand.