Responded to your PM.

After you check your transfer case with the drawings in the link I sent, you will know which transfer case you have.

A second question is what oil is used in that transfer case.

With the early E83 (X3) transfer cases, there were a series of fluid changes in the early production period. They went from ATF to a special fluid. I believe that they ended up with the same fluid that is now used in all of the other X-drive transfer cases, but they didn't necessarily start with it. We have generally referred here to all x-drive transfer cases as using the new fluid, but there may be a different fluid used in the very early ones, I don't know. I would be asking the service department, who can look up an technical bulletins (SIBs) myself. This is all a slightly different question than whether or not you have an x-drive transfer case, though.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue