All the trucks (and cars) I've owned, and all the trucks my father has owned have been manual. Three 1 tons, two 3/4's and some smaller ones.
When I drive an automatic car (not very often) one of the first things I inadvertently do when approaching a stop is slam on the brake while looking for the clutch pedal. They make the brake pedal so large it covers where the clutch pedal should be...

I don't think there is anything particularly wrong with modern automatics, in fact I'm quite impressed by the Allison 5 and 6 speed electronic ones.
But for now I really prefer a manual transmission.
That said I have intentionally used parts in my truck project with the idea of easily switching to a 3000 Allison if I ever want to in the future.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-