Pop out the rear plug to see if it is cam bearing that has pulled out. Then just tap on it. I see varnish rings on the bottom's of the lifters and it may just have a varnish ring on the back s of some cam journals that is hanging it in there. (You would not believe how hard /6 lifters can be to get out of their bores due to varnish rings; it often is hammer time....)
If the rear bearing really has pulled out, I'd go from underneath with a grinder and grind a slot in the bearing to release it from the rear cam journal. But you'd have to pull the crank and rear pistons. And then you have to see if that rear cam bearing spun in the bearing bore; it might not be fixable.
Are you sure it is hanging on a bearing, or just has dropped down and is hanging up on a lobe?
