Heres the issue ive just built up a repairable write off car 03 BA auto with a killer engine. Now the nsw gov has changed the law and it is now demed a stat write off so now rego is near impossible . So I have purchased a 03 xr6t auto standard cheap and would like to swap my engine into the new found car, so I will need to bring over the ecu to keep the tune with it. My question is what other control units will have to come with it so there is no serial number conflics and security code violations? Im thinking premium sound and some sort of body management control.

From what I understand you will either need to swap everything so it all matches or you can just do ecu and get ford to sort it out for you. Cost vs PITA I would just get ford to sort it out.