<VV> Idle Vibration

[Padgett]

Now that it will idle, there is an annoying vibration that is not excessive 
(barely feel in steering wheel) but enough to rattle things between 600 and 
750 rpm. Below and above it goes away.  Just replaced the balancer with a 
Dale unit and grabbing/wiggling the flex plate (PG) through the access hole 
it does not feel loose or unusual. Have no reason to think the engine has 
ever been separated from the engine. ODO reads 74k but who knows. Is this 
common or where should I be looking ?

Padgett