I'm wanting some input on getting new gears in my truck. I know I'll be hauling around 7000lbs. Right now my truck has stock 4:10 gears and it is horrible at towing on flat ground it does fine but the moment I hit a hill I'm done to a crawl and last time I towed I barely made it up the hill granted I was towing 13000lbs. So what would better gears to tow that won't kill my gas. I have a 99 ram 5.9 with 285 75 16 tires.