Interesting. I have a 6.2 with 4.10 gears, and no overdrive and while it maxes out close to 72 mph, there's no reason my K-5 should ever go that fast.
I've driven several 6.2's with 4.10 gears and stock size tires with no overdrive and they use almost the same amount of fuel vs the ones with overdrive and 3.42 gears. Are they louder, yes, it's a product of owning a indirect injected Diesel.
I can say the non overdrive trucks lasted longer and worked better for me. The old 6.2's if not turbo'd love to run at near 3000 rpms. They'll do that all day long without issue.
I know guys with 6.2's with no overdrive and 4.56 gears that max out at 62 mph. Still works great, loud, but pulls a trailer better than just about any other 6.2 out there.
To each his own.
05 2500HD CC LB LLY, 4x4, 3.73s 235/85R16's, webasto cab heater, to keep it warm.
03 Buick Rendezvous - When you average over 80 miles per day driving around, you need one of these.
85 K-5, 6.2, SM465, Rockwell T221, 1 tons, 36's. More goodies to be installed as time and money allows.
82 K20, 6.2, SM465, NP208, stock except for bed rack, snow plow, and glow plugs are on a toggle switch. It works great for plowing!
72 Postal Jeep - Yet another project