These Advance Adapters Saturn overdrive units are a great addition to early Jeeps from 1940-71 and International Harvester Scouts from 1961-65 using the Dana 18 model transfer case. They offer you the needed gearing that the early Jeeps were lacking. The Advance Adapters Saturn overdrive units are fully synchronized to allow for shifting while the vehicle is in motion. Are you putting a V8 engine in your early model Jeep? Don't worry; these Advance Adapters Saturn overdrive units can handle up to 300 ft.-lbs. of torque! Shifter linkage and handles are sold separately.