Thanks for the reply's. Fordmdb, I've seen that you've reported getting 16-18hwy and 12-14city with your 4.3 axle (even with the heavy foot you seem to have [I've seen the video] ). Ford56528, I believe you have the 3.73 and have seen 12-14 in town. What have you seen hwy? I saw someone reported 15-16city and 16-18hwy with the 3.73. If these numbers are more widely seen, seems with the size of camper I have, I just as well go with the 4.3 given mileage doesn't seem to be impacted much.