ECU differences?

[canada karl]

What would happen if I swap in a 1976 E12 ECU into a 1977 E12 with 77 ECU? 76 is 5 speed and 77 is Auto otherwise the cars are virtually the same. The only difference being the "last digit" in the code number on the ECU? Would it likely work or would I somehow do damage to internal wiring?

[Mike W.]

If you're referring to the 002 and 004 ECUs, they are interchangeable. I suppose there must be some difference, but I have no idea what. If you're talking 528i ECUs, those I would not interchange.