Mark Charters posted a message about Re: random unit in reply to Re: random unit
There are the crates, but again its all from a list and RA2 probably uses some complex formula in the .EXE file to work out which unit should appear (most 'random' things in a game are the result of a list and some complex maths). As I said, you could edit the Secret Lab or try editing the crates (it is possible to create a suicide unit that always leaves a crate behind for example).