Traxxas Primary Gears T-Maxx This is the replacement primary gear set for the Traxxas T-Maxx 4WD Radio Control Monster Truck. This gear set is installed on the primary gear shaft in the transmission. Replaces damaged or worn primary gears. Plastic. INCLUDED: One 28 tooth forward and one 22 tooth reverse gear One 2x9.8mm steel drive pin One 5x10x0.5mm teflon washer