goedemiddag meneer!,
I can only inform you about the B737-300 u/i 900 aircraft.
As far as I know (and seem to recall) the pax version of above mentioned types are already equipped with a F/O sliding window that can be opened from the outside (so no need to add this feature when converting into 737C )
All the best,
NB
PS, For some detailed reference I find
http://www.b737.co.uk/ very usefull.