Sent you an ipl and service manual. But that number isn't in the ipls. The number is not listed for the clutch drum. But did see thisI have a service manual and parts manual for early 066 and parts manual for later 066 but it not in any of those parts manuals.
https://www.amazon.com/Clutch-Sprocket-Stihl-Chainsaw-MS660/dp/B013GVIAHY