There are differences with firmware, but I've not really identified what differences are seen with diff versions. It MIGHT be that later firmware deals better with turning off the CD when selecting Sirius mode...
I don't know what coding actually does- broadly it ensures that software codable features in the car or modules are all properly configured.
boostmiester had been looking to buy a unit from the EU- not sure if he did, there were some issues with unresolved questions about compatability.
I assumed you've asked for pictures/closeups of the labels on the units- that will have part #, and firmware revisions... f
I have but have not received any as yet, but not that I would know if it was compatible or not ... the local dealer did not really know either .. they have a part number that they order, but that is not to say that another number may not work either, as the same computer can be used in different kits (like retrofit kits) but still have the same internals.
Firmware is an interesting problem, how would one know if the firmware is compatible for an E39, if the unit for example comes from a Z4