The 4010 and VERY early (IIRC, pre-'65) 4020 tractors DO have a 3rd reverse. The later early models and on only have 2 reverse gears that are sped up.Synchro locks trans in two gears for park. No cable needed. Ever notice the synchro has a reverse in the 4/7 slot when the wear gets right? Not marked on the dash but works. Makes for a high speed back up!