I always thought that too...but this crank on the 2.5L is smmoooooth on the inside, about the size of half a golfball. there is a rollerbearing in the flywheel, carries the shaft going into the transmission. maybe it is a thing with the early 90s 4cyl. the pilot bearing that comes in the clutch kit fits nicely in the center of the flywheel...three easy raps drive it into place.
91 YJ Runs 79 CJ5 waiting for winter
YJ - one step away from a CJ = lots of interchangeable parts.
TJ - one step away from a JK = sudden urge to go to the mall