Not that I want to argue, but what makes these models better than the 05 and 06?
Argue was the wrong word to use, "debatable" would be better. I was responding at some unholy hour of the morning when I couldn't fall asleep.
Early 03 and 04 Trucks have some key differences compared to the trucks following the 04.5+ model year. I had a written a small dissertation out in response but I'll just condense it for simplicity's sake to keep on topic in the thread.
Early 03 04 HO Dodge 5.9 Cummins Trucks (E0304)
Piston bowl design(injector nozzle)/ : 04.5+ to 07 trucks have a different piston and nozzle combination compared to the E0304 HO trucks. The bowl and injector design was a hardware change towards more emission compliance trucks during the third generation Dodge Cummins truck platform. The pistons weren't as robust and durable and they commonly break and snap rings in stock applications within the first quarter million miles on the engine. E0304 HO trucks have a higher HP piston design capable of supporting additional power(durability) and heat. 04.5+ trucks have a different injector nozzle that needs to be paired with their piston bowl design. E0304 HO pistons and injectors are forwards compatible in late model 5.9 blocks but they must be paired with their respective nozzle.
Pilot Injection: 04.5+ trucks had additional pilot injection events per combustion cycle in comparison to the E0304 trucks. This was also an emissions compliance change. But the additional pilot injection events put alot of wear and tear on injectors, a leaky tip or over fueling injector can easily snap rings on a cylinder. Even more so on the lesser designed pistons. 04.5+ trucks with stock programing cannot get by on worn injectors as long as the E0304 trucks. Fuel system filtration is critical for any common rail system but the 04.5+ trucks were even more susceptible to failure with their bowl and nozzle design. The additional pilot injection puts more stress on top of this.
NV5600: E0304 HO trucks came standard with a NV5600 6 speed manual transmission until auto options were available. People will lean one way or the other about how they shift or drive but objectively they are stronger more durable units out the factory compared to the G56 Mercedes transmission that began implementation in 05.5+. Both units are medium duty in a light duty truck frame, neither will shift like a manual slap shift Honda.
Misc: E0304 trucks can be identified by the cylinder head mounted APP sensor housing and throttle linkage, this is a carry over from the second gen 24v VP44 trucks. 04.5+ trucks had the APP sensor relocated to a battery tray underside (drivers IIRC). The valve covers starting changing to the plastic tops in the later 5.9s with integrated CCV's similar to the 6.7s of the third and 4th generation. Some of the 04.5+ trucks have plastic end tank intercoolers from the factory. E0304 trucks were all aluminum. E0304 HO trucks are engine Vin C trucks.
TLDR: E0304 HO trucks can be likened to the robustness of the previous generations 12v, but better as a pre-emissions common rail truck. i.e. More precision, more power, better fuel economy, cleaner burn and the cherry on top is not having to deal with a piss filled Chrysler automatic transmission.
