Certainly appears to be a piece of the one of rubber 'rollers' in the Centa coupling. Poke around in the inspection hole in bottom of the engine to gearbox adaptor and you will likely find more pieces. I hope for your sake I'm wrong, but I wouldn't be taking any long trips....
Time to get a Centa upgrade set up from Phil Bleazey
What’s the worst case scenario here? Engine removal for roller replacement? Seems like a labor heavy job for very few parts.
