IMHO, if you want a good diesel with IH or Navistar stamped in the block, buy a DT-466C or earlier (mechanical versions). Those engines were THE engine to have in their heyday (70s and early 80s), owing to bulletproof construction and superior crossflow intake-exhaust path versus the JDs of the 70s. Having grown up on Red Power (you farmboys remember that phrase?) on the farm, I knew from experience a 466C could handle over 300HP. Dad's 5488 was turned up (fuel screw kept backing out) to over 300 HP from I think 180HP rated, and the dealer chief mech said it was like he'd set it up to go to the pulls. Told Dad he was afraid to put it on the 500HP side of the dyno. The engine kept burning EGT sensors.
Dad used to pull a 24 ft field cultivator in front of his planter, and when they backed it off to 230, it was a dog in the clay loam soil in the Evansville (IN) area bottoms. Pulling a 15 ft chisel plow, it would spin out before it would bog down. A neighbor farmer told Dad he knew when he saw the rolling smoke it was either Dad on the 54, or the coal train going to ALCOA.
Never had any engine issues, but have had to replace the gears, and we knew that was expected, based on a discussion with a dealer mechanic in Yale, IL about 5 years or so before we did it.