Welcome to the forums, John. You've found a vast storehouse of info on old Chevy and GMC trucks. A lot of your questions can be answered by using the 'search' function of the board. If you don't find it that way, there's probably someone on here who knows. You made a valuable contribution yourself by pointing out the school busses used the round guage assys for several years after they were changed on the trucks.
Concerning your PTO: most likely you have one PTO. Pull the knob out to engage the pump then use the "forward and aft" lever to raise or lower the bed.
