I was curious if I got the 5.3 engine, ECU and wire harness from a complete truck (2002) if I could put it all in my 2000 4.8L and run it off the stock 5.3 ECU? or would I have to mail the ECU out to get it retuned?

The 5.3 is all stock, I am just curious if there would be any conflicts with swapping the ECU from 4.8 to 5.3.