Looking for some general startup advice

If you are keep your speeds down then you could do 5.5. But if you run the speed limit then not a chance. You will be lucky to see 5 with that fuel pig.

But overall it is likely the most reliable, easy to fix on the mix. But they are also heavy. If you are leasing to someone I would check weight and length before buying the WS.

 

You're gonna need to drive slower to get mpg out of a truck with 3.70 rears. It will pull pretty good without sucking as much fuel as a truck with the 3.36 ratio. If you are running primarily In and out of the midwest I don't see low to mid 6's being a problem near the speed limit. Slow it down to where you can run it in 12th and I bet you'd see high 6's. Of course without a warranty you are free to bypass the egr and put a box on it or have it tuned. With that, some supporting mods and a light foot, you'd be doing well even with the hood and stacks.

 

Have the lifetime mileage pulled off the truck to get an idea. With my 12.7 at 1425 and 70ish I get 6 all day long unless I am in hills and heavy. If I'm light, I get 7. On a recent trip from FL to WI to WA, I averaged 6+ with a big manure spreader on the back and 25k lbs. My 2000 WS 4964EX has a 12.7 430/470 putting 390 to the ground, 13 spd, 3.36 rears.