Highest Quality Hardened Steel gear set for the Baja. These gears are the best in the business. Designed to hold up to the punishment of big HP engines. **.  These lower ratio gear sets were designed for Blackbone two speeds as well as replacement sets for a stock Baja.   You will need a spur carrier if you do not have one.  You will also need a Blackbone clutch bell to run blackbone gears.