cracked flexplate sound but not cracked ?

[blazer2007]

update. Got new flex plate, starter, harmonic balancer and freshened up the dist. Still have the noise. Pulled plug wires one at a time while running and still the noise. Starter has lots of room when running but might throw a shim in there and see. Took valve covers off again and turned motor over with no ign. power and no noise and valve train all looked good. The next simple thing to try is mech. fuel pump. I,ve read alot of noises coming from there. I getting stumped without actually taking the motor apart which is OK if I have to do it. If you think of other tests I should try please let me know. The noise is the same at all times , hot or cold but only when running. Oil pressure is good