HMMM, Did i goof???

[RRtoRV]

A lot of talk about the gearing which is good. A point to remember is the overall truck mileage. It looks like you bought a truck with 3k miles. If that is true then it is still in its break-in and will get poorer mileage as a result. Remember, these are 400k engines and 3k is like driving it off the lot. I just sold a diesel pusher and the 8.9 Cummins at 15k bumped up another 1.5mpg just like that. My new 2011 6.7 diesel did the same thing at about 15k.
You will see a change when you get between 10k-15k.

[JFF&KRN]

Thanks to all for the info and please keep it coming as i am still learning and am glad those with the additional actual experience are chiming in. I have a 2006 chevy silverado that i use for my handyman business and it has 130,000miles on it and remember about 8 years ago i had to use it for a weekend trip as the other one was in the shop. I recall getting about 10 mpg with it, and it stays that way to this day, loaded, empty, up hill down hill etc. So in hopes as time goes on, the mileage gets a little better and of course within the next few trips i should be able to find it's sweet spot. I maight add one more thing to the equation, tow haul mode seemed to do a better job when i left it in regular drive, than when i used the manual shift. maybe i just use the manual shift as needed when descending the major hills. just some more HMMMMM What do you think things. Again Thanks and hope to see some of you on the road.