I'm with Bill, to a degree. With virtually all modern automatics having torque converter "lockup", eliminating entirely any slippage from the engine to the drivetrain, one of the old-school major objections to automatice is eliminated. And he's also right about overdrive lockout--modern automatics have pushbutton settings (mine's on the end of the shift lever) locking the transmission out of overdrive, which on mine, also disables the "coast clutch". With the coast clutch disabled, you get real-world engine braking. Engine braking on a diesel is rather more powerful than on a gasser. I can descend long 6-8% grades with very little braking if I lock out of overdrive at the top of the grade.
All of that said, when I shopped for a used 3/4 ton or 1-ton diesel 10 years ago, I wanted a manual. I just couldn't find one in the weeks of casual to active searching. They're rare back East. I fancied a manual mostly due to having suffered multiple auto trans failures on prior vehicles, all due to overheating during boat towing excursions (4 auto trans failures in all, from 1985 through 2002, and all but 1 in half-ton Suburbans, including twice in the same 'Burban!). My thinking was "get a manual trans and be DONE with trans failure always being in the back of my mind". Couldn't find one, and to top it all off, I bought a 2002 Ford 7.3 diesel with the notorious 4R100 automatic, known far and wide for torque converter failure at an early age. Must have gotten a good one, as now she's got 244,000 miles on the original 4R100 automatic.
Foy