I have a 5.4L RB 4WD and it's fine by me........it's geared slightly tall with 3.73's and 285/17's but I can't complain about the gas mileage......I tow a small motorcycle trailer with it fairly regularly. It's getting a bit heavy with a PH top and a home-brew interior.....I can put gas in the 5.4L for a few years for the cost of bulletproofing a diesel......