I have the NV5600 in mine with dana 60 front, dana 80 rear, with 3.55 gears and 285 series tires. My truck runs about 2,000 rpm at 70 mph

 

I going to have one of my law enforcment friends radar the truck, not sure of the accuracy,going from 245 to 265 tires going to get some kind of electronic box to change the shift points,exhaust brake,ultimately looking for better fuel milage maybe a little more power, I have to figure out how to post pics here, will get them on eventually