I have an even older version (late 70's I think) version of the boat your looking at. There are no drain holes in the transom above the deck level as standard. If there is a hole drilled in your transom, its a modification and will need an elephants trunk fitting.
I'm not referring to the large drain hole in the stern of the boat below deck level.
The hole and bung everyone is referring to is just before the transom in the deck. Its very efficient at filling the boat with water if you forget the bung

I have a bilge pump fitted to mine....and having stuffed it a few times, am contemplating fitting a trunk bailer now.
Good luck with it...they are awesome little ribs.