If you're tired of over revving your engine, the best resolution is a higher ratio Ring and Pinion gear. It improves mileage, increases engine life and makes for a quieter ride.
Larry Jackson, 805-441-2627, Is considering making ring & pinion gears with 3.36 ratio for 34 - 39 half ton trux. it also fits 34 - 36 Master Deluxe passenger cars. If you're interested, please call and let him know. He needs a run of 25 before he can start. If no one is interested, it won't happened.
If you have a 1930 - 32 Chevy, he has already made 3.50 gears for those, with many accolades from the purchasers.
Lou