[aerohead]

For the OEM truck, GM may have already 'optimized' the gearing, considering passing acceleration, hill climbing, full load, towing, etc..
To arbitrarily change it, you'd be completely shooting in the dark.
My CRX has three overdrive gears and 'ANY' headwind, road grade, passing maneuver, etc. requires a downshift to, as low as 3rd-gear, just to maintain a constant speed.
At Bonneville, I could never take it out of 3rd, as , if I did, the engine would completely come out of it's torque curve and fall on it's face. I'd go from 97.386-mph top speed, to 89.61-mph.
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I recommend that you exhaust all available avenues of research to see what other S-10 owners have experimented with, and all the outcomes.