Well you are a bit older than I. However raised on a farm myself. Along with 15 mins from local drag strip. Tons of engine builds along with transmission builds etc. And yes very familiar with Gear Vendors. I think you miss understand what im saying. I dont run 4000rpm on flat ground!! While towing. No need with 400flbs. However when Towing a trailer and fairly loaded box. Up 5-8% Grades, you need to keep the engine at or slightly above its torque peak!! This means second or third gear depending on grade and load. You absolutely should not be pulling steep grade while loaded at 3000rpm. Unless you want to risk losing a rod bearing or main do to fuel knock and Lugging. This can be safely sustained for 20mins or more as this is what the gas engines of modern design are built to withstand. This is why the 6.0l stayed in the HD for so long. Durability testing. The 6.2 420hp engine for example will not last under these same conditions as its built as more of a hot rod engine even though its in the 1/2ton trucks. Not sure why you think i would run above 4000rpm under all conditions? This is about towing and where I live. There is a ton of Mountains and no way around it. SO 4500rpm second gear around 7500lbs trailer and 2500lbs in the bed. Minimum 10 min straight on most trips. Have owned and built 6 small block 355 in half and 3/4 tons. First 2 are still around at over 200000km on the build tons of towing and work hours. Latest truck before my 16 was a 2001 2500hd Lq4 Basic rebuild when purchased along with trans rebuild. Cam/headers/ tune etc. Great towing truck! Sold at 250000km no leaks or repairs after my build. Towed great! Even picked up 3rd gear with the 4l80e doing the same towing up 8% grades, While at 110-120kmh in 3rd at 4500RPM. Each there own we all have our experiences! I hate diesels! and the FAD that they created. Great for working and if i towed 15000lbs daily I might own one. Or id Supercharge an LS. Peace.