6.4 lifter failure symptoms?

I thought the truck had a broken rocker. Pulled both covers to find all of them are good. There is a nice tick/tapping noise coming from the engine. No thumping through intake noise like a broken rocker does though. I think it dropped a lifter, just want to be sure. All pushrods are good.

drop oil, see if there is a bearing on the drain plug or in the pan. If not, than take the gerotor out and see if there are signs of bearings passing through