I just had a quick question. I just bought a M2 ecu from someone and there are no markings on the outside shell that say M2 worked on it. I opened up the casing and saw nothing spectacular. I tried looking to see if anyone had actually replaced anything on it and saw nothing. What's the deal? Should I be able to see any evidence of work that was done or is the ecu physically identical to the stock one?

Thanks in advance.