Ernie, here is a picture of the 794361-45100, I don't think you will find a used one. You can see that the 794361-45100 is not even close to being the same as the control valve on the YM1500. The control valve that Arron posted is the correct one. The one that I posted is suppose to replace the old one, but I can't see any way that it will work. The only tractor that I know the 794361-45100 will work on is the 650 JD, I'm sure that there are others.
Danny