Size of bolts holding pressure plate to flywheel?

Alright, replacing the clutch on a '94 cherokee right now. We've got the transmission/transfer case combo dropped out, but we're having trouble with the bolts that hold the pressure plate to the flywheel. What size are they? 12mm is too small, 13 is too big, and 1/2" is also too big. We've already rounded one of them off a bit trying different sizes.

So anybody that's done this before, what's the size?