My son has a 2008 silverado with a 5.3 it has the DOD thing where 4 cylinders shut down at speed,The engine is junk, but My other son has a 2003 Tahoe with a 5.3 Is there any way this 2003 engine will work in the 2008?

 

Should be ale to be i think you will need a new ECM or a way to delete cylinder shut down or deactivation.Likely a pro with the expensive tools can do that, or swap in a ECM without it. Perhaps that 2008 will do it itself.

 

I think you'd have to swap the computer too. Which means swapping the harness as well. And maybe transmission? Doesn't sound like a good idea.