if I remember correctly all E32 do have a coding plug in the backside of the OBC. (?)
On some E34 models the OBC needs a coding plug in the backside.
It maybe that this is only necessary on the EURO models which partly do not have a check control.
That is shown here with the coding plug installation
http://www.gunnar525.de/screwings/bc...ierstecker.pdf
another 56 pages instructions how to install a OBC, and it also shows all things which were available such as the clock, OBC III etc
http://www.gunnar525.de/screwings/bc4_einbau.pdf
FAQ OBC in German
http://www.gunnar525.de/screwings/bc4_faq.pdf
but I assume that in the U.S. models there were only OBC III and IV and all have the coding plug, so both should fit, but no guarantee