A few TO-35's were built WITHOUT live power (2-stage clutch) When you push the clutch down halfway, do you feel a second stage? If so' don't push the clutch any further and you'll still have hydraulics. If you found one without the 2-stage clutch, you WON'T have live hydraulics. A fair amount of Ferguson/Massey Fergusons and Fords of that generation had the option of 2-stage clutch or NOT.
Am I understanding you right that there are a total of THREE levers? If there's only TWO, one is lift control and the other is draft control lever. Not sure what a 3rd lever would be. I have an owners manual (in new condition) for that tractor. If interested, PM me and I'll give you the details on how to make it yours. If you have ANY intentions of keeping ANY tractor, I highly recommend an owners manual, service manual, and parts manual.