You will need to remove the transmission
from the flywheel housing. Then you will see the flex plate bolted to the flywheel, and it can be removed by removing the five fasteners holding it to the flywheel.
Of course this simple sounding procedure might entail sliding the engine
forward to remove the transmission
, or pushing the prop shaft back far enough for the transmission input shaft to clear the flywheel housing.....
Of course, if the "clack, clack" noise
is just in gear
at idle, you might just decide to avoid running the engine
at that RPM