I have googled and am seeing 17 or 19.5. Reason I ask is I have only owned the truck a few months and the sending unit was out when I bought it. The previous owner said he just fills it up whenever it hits 300 miles. I put a new fuel pump assembly in this weekend. I drove a little over 100 miles and it was around 3/4 tank. I was driving on a long drive on a state highway so probably getting max MPG's. The last two times I have calculated the mileage it is right at 20. I don't want to just run it out of gas to see how accurate the gauge is but if I can routinely go closer to 400 miles instead of 300 between fill ups that would be nice as well. Just curious how many miles you guys are getting per tank (if you calculate that) with a 3.0 automatic.