Thanks for all the help so far. I am still mystified as to how you know the SP1 and SP2 units are different, and whether all SP2 year/region units are the same. Again, searching the web & eBay, there are two advertised in the US; an 02 and an 03 SP2, but they have different numbers after the "MCF CI734". One has 2.9 121, the other 2.1 282 (see images below). Both different to mine and the SP1 unit. Apart from these numbers, all SP1 and SP2 units look physically identical; there are no other part numbers or identifiers, so how would you tell an SP1 and SP2 unit apart? And what are these additional numbers; are they just a date/issue code? Would any SP2 unit work in my bike (different year/region)? Sorry to drag this out but until I understand this a bit more, I'm reluctant to buy any unit for now.
(UK-spec. SP2, 2002 owned from new, 45k miles)