Stihl FS 90 crankcase seal material

Second owner of a FS 90 and I seemed to have broken all 3 mounts on the crankcase housing. Don't ask me how they all broke. Thing just started vibrating real bad and thought I'd better shut it down before parts started flying.

Found a replacement on good ol' ebay, but was wondering what you guys use for the seal when putting the new one on? I found something that I think may work called Permatex Ultra Black.

Thanks

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