This is a replacement ring and pinion gears from the front and rear axles.Replacement part for these models:TRX-4M™ 1/18 1979 Chevrolet® K10 High Trail Edition™TRX-4M™ 1/18 1979 Ford® F-150® High Trail Edition™TRX-4M™ 1/18 Ford® Bronco®TRX-4M™ 1/18 Land Rover® Defender®..