Ecm issue

[JTX]

Ok I haven't had the chance to change the wire harness but I did change the ecm to old one and the 4 codes disappeared but then this glaring scr derate showed up like you said.Now I'm not a mechanic I am just trying to get past this point and I dont have any problem doing that but I started it and it sounds definitely better with new ecm. So I'm just wondering if or would it be better to take truck and have ecm calibrated to this truck and then program like you said? Would that save a lot of work reprogramming for all that other stuff? Sorry if this is a stupid question but it seems feasible? If not I will get that wiring harness put on there? Just seems like there would be less programming required?