While I don't have any numbers to show, Oklahoma has lots of places that sell 100% gas. And, the price for the 100% is generally only maybe 30 to 40 cents difference between it and 10% ethanal gas.
When we were in Grants Pass, OR for 17 months, we had to buy a fair amount of 100% for small engines and ATV's. 100% gas was roughly $1.50 to $2.00 higher at times than 10% ethanol.
As for rear differential ratios, I used to drive for a company out of Greeley, CO called Shupe Brothers. Back in the '70's, most of their trucks were equipped with 335 Cummins diesel engines, manual 4X4 two-stick transmissions, and rear axles at 5:29 ratio. More than once, I had folks tell me that I wasn't making any money hauling empty. I generally got to tell them that I wasn't empty, but the truck had the where-with-all to get the job done.
That's why I like it that my 2008 Ford F450 has the 4:88 rear end.