6.4 Hemi Trucks

I have a 07 3500 crew cab with 5.9 and 6spd. avg around town has been 16-18

open hi-way it has seen about 19-21 as long as I stay under 2200 rpm
if I run 75-80 mph it gets about 15mpg.

it has 160k miles on it now and im second owner.
only draw back is the injectors. I replaced 3 already and think I have 1 on the way out now.
also the A/C sucks on these trucks