The issue with the rear seats is there was a change in the latches the hold the seat backs up to the c pillar. Again, I don't think it was a model year change but rather a production date change along the way. Realoem.com can probably pinpoint it for you.

The rear seatback latches have a hoop on the c pillar that goes into a slot on the seatback. On the early production setup, that hoop is bigger and requires a deeper slot in the seatback than the later setup. In order to fit the later seats in an early car, you'd have to disassemble a bit of the interior to change out the part that attaches to the c pillar. And, I think the trim pieces around those hoops were different, too.

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2012 xDrive35d
2001 BMW X5 3.0i 5MT
and two 1987 Corvettes - Callaway Twin Turbo and Guldstrand Grand Sport 80
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