5.9 or 6.7 Cummins

[Bucoo]

My buddy has a 6.7 dually automatic with grip tires cruising at about 60 he gets about 21-23 (deletes with edge). Dad has a 6.7 standard and going about 75 on the interstate with 35s he gets 19 or so without deletes. My brother has a 6.7 with 35s also with an automatic and gets over 20 mpg cruising on interstate and has gotten 25 mpg before (deletes with smarty). Either way you go ought to be good.