You probably already completed your task... but for the record.
I'm about to attempt this myself (for the 2nd time) the biggest advice I have is make sure you can knock the roll pin out (connects the shifter to transmission)... I left this to last when I attempted to salvage one, but could not get it free. In the end I had to abandon as the breakers yard was closing and wasn't able to return in suitable time frame.
Also someone mentioned Opposed Forces on another thread, seems like a great resource. And gives 'likely doner' list of cars to look for, note that there are 2 types on center diff.
For my Forester I found these compatible parts.
From memory you don't need to remove cross member, but I might be wrong. You will need to remove rear-dif cover, prop shaft (keep in one piece as it can slide out once pinon and carrier are unbolted) and exhaust shield.