Hi. Looking for some help deciding what to do and it's driving me nuts. Purchasing a 2021 lariat with 20" tires. I tow apx. 6K lbs and that's only occasionally with a dump trailer. I know I could get away with an F150 BUT I like the SuperDuty and I like Diesels. Mostly driven around town with some highways. I also live on top of a hill. One sales guy at the Dealership said to get the 3.55 and when his manager came over manager said to get the 3.31. Said I wouldn't notice any difference and I would get better fuel mileage. Leaning towards the 3.31 BUT wondering if it's really true. I know the truck has plenty of power BUT would you feel any difference when starting off? Not punching the pedal but normal driving. Does the gear ratios in the 10sp make them feel the same or driving normal would there be any seat of the pants noticeable difference between them both. Test driving two identical trucks with different gears would you be able to tell which one had the 3.55's? Is one better for around town driving? Appreciate the help...