I'd have to look over the wiring diagram again to be sure of any differences, but the primary difference is frequency.
Edit: a quick glance in the Bentley manual shows quite a few differences between the M531, M534, M535 and M536. Not sure what issues may arise, but I'd take Woody's word for it.
I spent a good hour looking through the workshop manuals, but didn't find anything. It's probably around 2000 pages long, though.
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