When I first got my xj I did an oil change and the gaskets. Of course all that good stuff. So when I pulled the bearing cap to change the rear main seal I noticed that it was pretty deeply scored. I don’t really know where to find, either a new bearing cap, or the scored plate.
That's the bearing. It should pop out. Just look for rear main bearings.
But first do some research on replacing them. By the way, the upper is also scored. Your crankshaft is probably also scored. Needs to come out. Take a look and you'll see it.