The GPM 51T centre differential spur gear is manufactured from hardened 40Cr carbon steel to withstand repeated torque cycles within the Traxxas Unlimited Desert Racer differential case. The hardened black finish increases surface durability while laser etched tooth count markings preserve correct meshing with existing drivetrain components. This part directly replaces factory items and part numbers #8573, #8574, and #8575 for a reliable service fit.