Not Pre-Mounted. Compatible with Traxxas TRX4M Bronco, TRX4M Defender, TRX4M Chevrolet K10 High Trail 1/18 RC Crawler
40.3:1 Ratio. TRX4M low range gear set made of quality steel, a solid improvement over stock. These gears give you that low end torque a crawler needs to go over everything especially in a bind.
Quality aluminum transmission housing replaces the plastic stock. Come with bearings for full usage.
Package Content: Transmission Case, Transmission Gears Set (with Bearings and Hardare for assembly)