Cummins flywheel hole? Oil leak? Mystery hole.
 

Greetings all,
Trying to diagnose an oil leak last weak on a rear engine Cummins 8.3L party bus last weak, I noticed a cap/plug or whatnot missing from the bottom of the flywheel area.

Bear with me here, I don't know much about this.

2 Questions
1)I'm assuming this hole should have a plug in it, it seems like dirt and crud can get in there? How the heck do I go about finding the right size thread/cap?

2)There's quite a bit of oil around this hole, is it possible that some oil is leaking through this crazy hole?
http://www.flickr.com/photos/109854540@N03/11061663183/

http://www.flickr.com/photos/109854540@N03/11061604225/

Most likely the hole is suppose to be there. No plug goes in it. Probably just a place to insert a bar to turn the flywheel if need be. It could be a rear main seal leaking. Keep an eye on the oil level and see if its a minor leak or major.

It probably is a freezeplug but i cant see the pictures

If it is on the back of the flywheel towards the engine side it is the barring hole. This, like tbirdz said is for barring over the engine by way of the flywheel. Most of them do have a plug in them, but as time goes on they can become lost or misplaced.

*Barring hole is #2 in the diagram.