On PTO's like Dave mentioned, you have the following choices on those old Fords:
Transmission Driven: (Used on 4/1 speed trannys). Is just that. If the output shaft of the tranny is rolling, so is the PTO if you have selector lever in the PTO position.
Live: Has 2 clutches and they are setup so that one works at the upper pedal travel points (the drive clutch) and the other works at the clutch pedal mid-position (if it is setup correctly) and is the PTO clutch. Usage of this would best be described in post hole digging.
Position the tractor with the auger where you want to dig the hole with the engine running and in a drive gear, clutch fully depressed.
Engage the PTO with the engagement lever. Let the clutch out slowly and as you get around half way released, the PTO starts rotating. Keep the clutch pedal at mid travel position.
Proceeding through the digging, you see that the auger has developed a tilt. With the tractor tranny in the desiged gear (F-R) slowly let the pedal out the rest of the way, moving the tractor in the desired direction and when there back to mid position......the PTO remains running the whole time. (You can't do this with a Tranny driven PTO.) When finished digging, depress the clutch all the way, lift the auger out of the hole and rapidly release the clutch to mid position causing the auger to start instantly and throw the cuttings off to the side.
Independent PTO: Just what the name implies. You have a PTO lever that you can move and get the PTO to rotate, regardless of everything else, except the tractor has to be running. It is hydraulically driven and all you need is the engine running to spin the hyd. pump.
SOS: Which is a power shifted "automatic type" transmission. Tractors equipped with this tranny use an Independent PTO. Lever is several inches to the right of the steering column about half way down the sheet metal shroud.
You have a gear selector and an "inching pedal" that looks and acts like a conventional clutch. Actually it removes the hyd fluid pressure from the tranny and the tractor stops rolling under power. Push it down like you would if you had a normal clutching type tractor but to shift gears, just move the gear selector. Had 10 forward and 2 reverse gears.