Android1

Is it necessary to change out a 1998 ECM for a 2004 ECM after swapping the engine? My mechanic tells me I have to change the ECM in my car. It is a 1998 GT with a 2004 GT engine and trans installed. The person who sold the car to me told me he had the computer reflashed(whatever that means). Should I go ahead and order the computer?

Thanks

uberstang1

No you don't have to change it, it sounds like the previous ownder had the ecm and car tuned.