clicking noise

[teeph]

I have a 1979 chevy truck with a 350 engine.  It has developed a clicking noise.  I first thought it was a burned up header gasket, so I changed that and noise is still there.  It is definitly coming from the passenger side of the engine.  The strange thing is that when you rev the engine in park the noise doesn't get any louder, but when you rev it up in drive or reverse the noise gets louder with the higher rpm's.  Please help.

Jeff

[mjolinar]

check your flex plate for cracks if you have an automatic transmission.