It's my pet peeve. I'm 60+ and don't call the 5.9 Magnum a 360 (LA) because I know different. If I'm at my favorite box store and I get parts for a 318/360(LA) they won't fit a 5.2/5.9 Magnum and vice versa.

From my favorite search engine.

Dodge/Mopar 360 (LA Series):

• Cylinder Heads:
  Uses earlier-style cylinder heads with less efficient combustion and potentially lower horsepower potential.
• Valvetrain:
  Employs a 1.5:1 rocker arm arrangement with shaft-mounted rockers, requiring oiling via the block and heads.
• Fuel System:
  Carbureted, relying on vacuum lines and other mechanical components for fuel delivery.
• External Balancing:
  Uses a special harmonic damper and flywheel for its external balancing system.
• Power Output:
  Typically produced less horsepower than the Magnum, though capable of being tuned for more power.

Dodge/Mopar 5.9 Magnum:

• Cylinder Heads:
  Features more modern, high-flow cylinder heads designed for better combustion and performance.
• Valvetrain:
  Utilizes 1.6:1 pedestal rocker arms and pushrod oiling, offering higher valve speed and potentially better performance.
• Fuel System:
  Fuel-injected, relying on a computer for precise fuel delivery and timing.
• External Balancing:
  Uses a different external balancing system, requiring unique components like a flywheel or torque converter.
• Power Output:
  Generally produces more horsepower than the 360 due to its improved design and fuel injection.

In essence, the 5.9 Magnum represents a significant advancement in technology and performance compared to the older LA-series 360, offering better fuel efficiency, power, and emissions control.