Ford had a better idea in their 10.5 corporate (Sterling) rear axle, no drain plug so you have to pull the rear cover to change the gear oil. Not bad with the Dana 60 high pinion in the front. It has a drain plug. Everything has grease fittings too. I love grease fittings. I hate to change non greaseable suspension parts.
I run a Hayden 12 pass heavy duty transmission cooler and have since the truck was new. I bought it to haul with so it's necessary to have the proper cooling. Heat is what destroys transmissions, inherent operation heat and heat from the shifting of the clutch packs.
I sometimes think about checking out a new truck with all the fancy dan stuff like tow-haul mode and engine brakes but that lack of a payment book always wins me over.
...and I actually have vent windows, something that Detroit forgot on newer trucks.
Like I said, you'll probably see my truck on a Rock Auto sticky magnet sometime.