It's barely flexible and feels like very hard plastic

 

Looks like the edge of the rubber gasket that seals the valley pan lip (front and back of low part of valley), it rides across there like a saddle. Mine were falling apart and hard when I pulled them off as part of the HG work. Unless you pull the valley pan (and intake) you won't be able to see the inside edge.

http://www.cannibalv8.com/cv8-instal...sket-end-seals

 

it does look like it is part of an old gasket, I'm surprise it would give you a noise.
but it quite well could have been getting sucked into the pickup like you say.
you appear to have a lot of baked on oil deposits was that thing over heated a couple times?

 

Also, for that noise to be heard above the operating noise of the engine.... perhaps you should look further. And do renew the gasket for the pickup and loctite the bolts....

 

Yeah, the more I replay the video the more I'm doubting that was it. I guess I'll be ordering some bearings today. If I have to remove the timing cover I might as well do the timing chain as well.

Drowssap, it did over heat but to what extent I don't know. The head gaskets were replaced about 10k miles ago just before I bought it. That means the valley gasket was too, which would explain a large piece of it in the oil pan.

 

it possible that piece of gasket was starving the oil pump, which would give you oil pressure problems causing the engine to rap. When you shut the truck off the gasket would fall from the pickup down into the pan, only to happen over and over.
if you going to do the chain do yourself a favor and chain out the pump, your already there.

 

Look thru https://landroverforums.com/forum/di...rite-up-48197/

Also, you'll want to look for problems with connecting rods and grudgeon pin (wrist pin in US).

The front cover kit without chain is like $112 (has oil pump).

 

Here's a pix of where I think your piece came from, if the valley pan lip seal is tightened too far this rubber gasket could be sliced off... There would be 4 of them possibly.

 

While I wait for my parts to get here late next week I put the oil pan back on and started pulling plugs one at a time it gets very loud and rhythmic when I pull the number 1 wire. Slipped Sleeve? Would the sleeve knock that much louder with no sprak?

 

Man thats loud. Is that the method to detecting whick cylinder is the prob? I thought the actual spark plug was supposed to be pulled!?