The 535 (Europe only), E34 540 (5spd) , E39 540/M5 (6spd), 740i (Europe only) and the 840csi all share the same/similar manual transmission. I'm currently converting my 740iL to a 6spd, but its not as easy as simply bolting the trans and driving. I have to order parts only available in Europe...new brake and clutch pedal set, master and slave cylinders for the clutch, transmission itself and a custom made driveline. The way around the computer for 7 owners is to flash the ECU w/ 540 software so it doesn't freak out and give 'Trans Failsafe Error' codes everyday while driving it. The problem w/ the X5 as Swiss mentioned is the transfer case and the X being AWD, then you've got a while different issue w/ the ECU since the only X in a 5spd is the 3.0. If you converted it to a RWD only and bypassed the AWD (god only knows how the computer would react, let alone if it'd even run correctly w/o seeing the transmission) system all together. Unless you're willing to spend at least 2-3k in parts (lowball estimate), you'd be able to bolt a 6spd to your X. Your honestly better off getting onto Car-Part.com--Used Auto Parts Market or Bavarian Engine Exchange & Rebuilt BMW Parts 's junkyard division and buying a used trans if you're not willing to fix the one you have now. Shops like Koala Motorsports quote at least $10k to do this job, but I'm doing the work myself, so i'll be into it about 1/4 to 1/2 that after its all said and done.

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