Good morning, I have a few questions about some problems I have encountered. So First off I want to say that I just recently bought a 2004.5 3500 4x4 SRW AUTO without a engine. Then I bought a engine out of a 2003 2500 4x2 SRW AUTO. I am currently stuck at if this motor swap will even continue to work. I finally got the motor in after changing motor mount brackets and now the truck isn't wanting to run correctly. I have both of the trucks computers and wiring harness but I don't have the 04 style injectors. Will this truck ever be able to run with the motor and computer from the 03 or will I have to change all the injectors and get the ecm flashed? Any insight on this would be greatly appreciated as to I have read countless hours over this truck in the last 7 months.

 

I've never done a swap personally but I am sure you need to use the 03 wiring harness with the 03 motor. The file types for the newer model will not work. You will also want that computer flashed to match vehicle vin.

I am not sure what that means for other accessories/options on the truck as the computer may not support them all

 

Thanks for your input. The problem I'm having with using the 03 harness is that it will not match up with the cab side harness. It's the same style plug but with different wiring. So now I'm thinking of just using the 04 harness and just changing out a couple plugs that don't match up on the motor and having my computer flashed to the 03 motor. I just wonder if changing the plugs will make any difference at all. Cause the ones I will have to change are very similar just mostly different in size but everything else matches up.