What is your "typical" ratio rear end (4.11)?
What is the "typical" rolling-diameter of your (rear) tires (30")?
These "calculators" might help?Especially the one at the bottom of the page.
4.11 rear end (216.5 engine?)
30" rear-tire rolling diameter?
90 mph?
1:1 final gear ratio with transmission high gear?
= 4143 RPMs - a very high long-term RPM in my world (you'd get maybe 10 mpg? I guess)
You might be interested in this graph - if you have not seen it (and if it pertains to your truck)?
