Trying to figure out if I will need to regear my rear end

[Jason Banks]

That'll be the gas mileage king with 3:08. I have the same combo 6.0 and 4L80e with 3:73 rear gears. It is totally comfortable at highway speeds(relatively low rpm) and will go 100mph effortlessly.

I'd say get it running the the 3:08 and see how you like it. If you want more performance change it then.

I only ever had one truck with 3:08 rear end was at 402 big block with a 3 on the tree. It was a great highway truck, even without overdrive.