Thanks for your info. Glad you got it going.
General rule of thumb for E38 ECM's and OS's:
- pre-2009 is not compatible with 2009 and post-2009.
- post-2009 is not compatible with 2009 and pre-2009.
Yes what Joecar says is correct. Anything out of 06/07 12597121 stays there. Early 06 E38 = kryptonite. (12603892? IIRC - careful) 08-12612384 09-12625455 10+ 12633238.
E38 got planned 03-04 - took till 10 to get them sorted so they didn't need to change them every year LOL.
Z06 E38's are an exception to this. Even more complicated. Best not to juggle them.