OK, let’s start this off by listing all the cons to installing a Gear Vendors under/overdrive in your vehicle. For starters, it adds 12.25 inches to the rear of your drivetrain. Done. Oh, unless you’re talking about a long-wheelbase vehicle that can benefit from having the rear driveshaft shortened by about a foot. Then you can add that to the advantages.
As for the pros, get comfortable because the list ain’t short. The Gear Vendors under/overdrive is an extremely heavy-duty auxiliary transmission that’s easy to install, gives you an 0.78:1 underdrive or overdrive, can improve your fuel mileage up to 20 percent, extends engine life by allowing your engine to turn more slowly at a given road speed, makes towing up grades easier, can handle up to 1,200 horsepower, is…