1987 Ford 6610 Tractor Rearend Ring & Pinion Gear Set D5NN4668A C7NN4206A Posted onApril 19, 2024AuthoradminCategoriesfordTagsc7nn4206a, d5nn4668a, ford, gear, pinion, rearend, ring, tractor Up for sale is a ring and pinion gear set. It came off a 1987 Ford 6610 tractor. They appear to be in good condition. The pinion has 7 teeth and the ring gear has 37 teeth. What you see is what you get.