I would not go more than 4.56 gears for two reasons. One, anything lower would be ridiculous on the highway, and two, you would have to get a larger carrier for anything lower. Also, if you are putting in a lunch box locker, I would recommend doing it to the rear, as it will make your steering much harder, and decrease your turning radius, if you put it on your front axle. I know that the rear axle is the weaker one, but it shouldn't be a problem with 33" tires. When you climb something, most of your weight goes towards the rear axle anyway, so I would think this would be the best place to have one locker.