Confused on rear disk part #s

[teahead]

Doing a rear disk swap on this 2800.

What rotors interchange?

I'd like to get some cheap ones like these:

http://www.ebay.com/itm/201477668831?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

But that part #

coincides with an E12:

http://www.realoem.com/bmw/enUS/partxref?q=34211119566

Yet REALOEM shows this part # for the CS:
34211165253



http://www.realoem.com/bmw/enUS/par...30CS&mg=34&sg=10&diagId=34_0845&q=34211165253


Anyone TRY to get the cheaper E12 rotors to work?


Could the picture here be bogus and it not really be vented?

http://www.bavauto.com/fland.asp?pa...QjvFpXnLUK09Ioh5ccf2XMNdsvO1wrVn6UaAsKl8P8HAQ

 

[teahead]

Or maybe these:

http://www.ebay.com/itm/BMW-630-633...ash=item4afcafdb58:g:uHoAAOSw-RRXBws7&vxp=mtr