manual transmition question

I have a 1995 b3000. 3.0 litre and i was looking at the trans yesterday and i saw this big hole like kinda towards the front of the trans. but when you look in to the hole you can see the clutch and flywheel. the hole is like 2 inches long and 1 inch wide. if you no anything please let me no.

Probably an inspection hole. Should be covered with a rubber plug. Am working on a '96 B3000 for a friend and his has a rubber plug in a hole like that. It is on the same side (but a bit lower) as the hydraulic line and bleed screw, right?