So im kind of a diesel guy i guess.
I own a ‘96 dodge 3/4 ton (converted to a 1 ton) with the 5.9L 12v, and “p-pump” injection pump. It is fully mechanical, and requires no ECM to operate. I use it for hauling pipe and equipment when i do utility work. People who refer to themselves as diesel guys will know what motor im talking about.
As far as ease of repair, they dont get any easier than that one. The entire motor was designed to be taken apart with basic hand tools - sockets, wrenches, screwdrivers. No specialty tools/fasteners/etc. Its more or less the holy grail when it comes to light duty diesels because of its ease of repair, being damn near bulletproof in its stock form, and ability to be modded easily and put up astronomical torque and horsepower numbers. I got my stock 190 horse, 440lb-ft 5.9 up to about 450 horses and 875-900lb-ft of torque with a half days work and a few hundred bucks worth of parts in my driveway.
That said, light duty diesels like the powerstroke, duramax and the ‘new’ Cummins are less end user friendly than ever. Im not a major wrench turner so my knowledge is extremely limited, but there are enough electronics on modern light duty diesels to require oscilloscopes and logic analyzers. Gone are the days of guys like me, with just enough mechanical knowledge and access to alldata to get by without visiting an actual mechanic.
i probably sound like a boomer saying all that but its my opinion, anyway.