My '99 2500LD ECLB 6.0 4.10 rear end averaged 14mpg on the highway at 65-70mph. I got 18 once running 55mph on a flat road, that was a freak of nature though.
Frankly I was a tad disappointed because the truck it replaced, '84 K20, RCLB, 3 speed handshaker, 5.7, 3.42 rear end, could...