Gears? Yes...
When I was doing a lot of towing with my 04 2wd regular cab I put 4.56's in with stock height tires (265/70-17) and it was incredible. Don't go over 65 though if you're concerned with mileage. That was with stock-ish tires though. With an empty bed if you floored it, it would spin the tires for 15-20 feet. That's without brake locking it. Brake lock it and... Well... My lawyer advised me not to talk about that...
I moved and started using the truck as a commuter and went to 3.90 gears. I really wanted 4.10's but they were back ordered and I was kind of limited on when I could have the truck in the shop.
I wish I knew what LSD I put in it, it's awesome. It's really tight and if you make tight turns like in a parking lot and hit the gas a little it squeals the inside tire.
Back to the gears, with 35's I wouldn't hesitate for a second to put 4.56's in. You will need a notched cross shaft though. The gears are so thick you have to put the cross shaft in, then put the gear on, then you rotate the cross shaft to get the C clips in when you put the axles in.