The prechamber is in the head. It's the thing the injector screws into. Nothing to do with the IP. There's something of a metal washer that seals the injector tip against the prechamber. That's the heat shield. You can fish it out with a hook or a magnet or crank the engine and watch it fly into oblivion.

Noises resonate througout these engines so I wouldn't trust ears. The clacking could simply be a serpentine belt tensioner damper Heim end that's worn out. Lots of folks have mistaken the noise for nailing or rod knock. Don't trust your ears! Loosen each injector line one at a time to see if you can isolate the noise and/or smoke. A full turn or two until fuel dribbles from the junction is all you need.

I performance isn't affected, maybe you lost an exhaust valve seal or turbine/hot side seal.

Sixto
87 300D