Not to sure what this leak is

[TcS Trippin]

Hey just purchased a lovely 2.5L M54 Z4 found this leak but not to sure what it could be really hope its not the main rear seal but any help would be great!!

 

[Trevor /chedder]

Sump bolt looks wet. Wonder if they replaced the o ring when they did an oil change?

 

[bmwz3tower]

I've got a similar leak on my getrag box, and I think its the selector shaft seal. I presume the ZF would be similar