i have 4.10's w/ 35's. and its almost too much. but i love them. cuz it does pull trailers alot easier. i don't recommend 4.56's because that would be just way too much JMO. i remember reading an article of a guy who was doing 12's on 1/4mile on 4.56's but he was rock'n some 40's. ofcourse his rig was like totally built up for it.i really didnt want to go threw all the work of changing gears and still have the rpm's lower than stock. every gear company that i have talked to said the same thing go with the 4.56. its ony going to be 70rpms over stock. i just want to get that bottom end back i had when its was stock.
4.10's w/35's pretty much puts you to stock(3.7?'s). not exactly 3.73's but pretty dam close. and the guy is recommending the 4.56's because that''s what they do all day to gas vehicles, and diesel s have way more torque than gas. good luck, but i recommend 4.10's. i still get up to 20mpgs empty on highway at 65mph's and about 12mpgs with a 13000lbs trailer going 55-60mph