Trying to help my Dad again. He dropped a valve seat in his 04.5. He got a smoking deal on a Cummins reman long block and head. Turns out the long block is an '03 with the 305/555 specs.
The guy doing the swap said it won't work unless he does a bore and piston swap to upgrade the '03 long block.
My question is; will dropping in the 2003 long block work? What is the difference? Could he do it if he had an ecm from a matching manual transmission 2003 truck? If he can use the new long block, I imagine the 2004.5 head will work.
Thanks in advance.

 

The heads are a direct swap. The original 2004.5 heads are better than the original 2003 & early 2004 heads. Better valve seats & exhaust valves.

The 2003 & early 2004 engines had different piston bowsl than the 2004.5+ engines. The original injector tips must be matched to the corresponding piston bowls.

You could drop in the entire 2003 engine into the 2004.5 truck. Keep the 2003 injector tips. Keep the original 2004.5 ECM, sensors & harness.
Plus keep the 2004.5 turbo. The 2003 turbo is very small.

 

^^^ Yep, what he said. Only difference is the injector tips and piston bowls....they have to correspond!!!! Use the '03 long block with the '04.5 head but use the '03 injectors and you should be good to go.