engine change
 

recently i installed a 79 model engine in my 84 300d. engine runs like a kitten. but at high rpm i hear a clanking noise like flywheel hitting something but only at high rpm is the flex plate coming in contact with the bell housing give me a clue please

need more to pinpoint
 

The spacer plate on the back of the engine(auto) needs to be perfectly aligned-ref engine manual-. Is everything tight back there? Could be quite a few things. Sorry to be so vague, Paul

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'84 300CD 290,000