10 miles is a long way to drive on a 60 year old tractor at top speed that you are unsure of it's condition. I got a 861D with that 5 speed in it. It can be a pain to find the gears in. You should have 4 forward speeds and a reverse. I
Bad info!
A 5 speed has 5 forward speeds AND reverse.
Please learn how to use a 5spd shifter!
top gate, shifter forward is 3rd, aft is reverse, middle is neutral.
middle gate, is 1 N 2
lower gate is 4 N 5