[Tiago]

I'm tracking a gearbox solution for years.

Manual gearbox: we can find manual gearboxes in other versions of the m57 that is a direct fit for our cars, like x25d (3.0d) and x30d. There isn't any manual x35d, in US or Europe. The conversion is quite simple as you just need to delete the auto gearbox from ecu. The clutch pedals and all other things is a plug and play retrofit from the manual m57 cars. There is also several solutions to reinforce the manual clutch to handle insane torque levels. The only issue is the lower top end speed because stock gearbox is able to +200mph and with manual m57 it will be reduced to 160mph. There is 35d engine swaps for others car brands with huge sucess. One of them is on 4x4 Nissan Patrol with a special plate adapter for his Y61 gearbox.

Auto gearbox: you can't use the newer bmw gearboxes because you have to marry the gearbox software with car ecu software and this is just not possible. The only option is to make a special adapter plate for a aftermarket auto gearbox with independent software and hardware controllers and erase that function from car ecu like if with a manual gearbox. The other option is to send our gearboxes to australia because they are used to reinforce this gearboxes with 6r80 parts and others special parts on their 7sec cars with +1000rwhp and +1000rwtq Ford Falcons which share the ZF 6hp26. They also cracked the software and are able to tune their gearboxes. But the bmw software is at other level and is still a mystery for the common world. This solution without the software tune is the best but be prepared for +$20k.