I have a 2003 F350 with a 8" lift, on 37" tires. The gears are the stock 3.73's. I tow a 17k pound 5er and I'm debating about regearing to 4:56's and keep the lift and tires or put a 4" lift on and run 35" tires. My question is, will I see much difference between the 35's and 37's?