If you are only going to be running 33inch tires, then you certainly don't need 5.29's. You may want to use a 4.56 but nothing lower than a 4.88
Consider a mountain bike shifter with 4 sprockets. The gears you have in your truck right now would be the equivelent of using the larger sprocket; it takes more energy to get going in that gear, but once you are up to a cruising speed it will roll along nicely as long as you dont hit any inclines or head wind. The smallest sprocket would be like running a set of 5.29's; it takes almost no energy to reach its top speed and easily maintains that speed through inclines and head wind, but the top speed is slower and less efficient than the larger sprockets.
It's a balacing act of performance and fuel efficiency.
