Weird sound coming from trans

[ScottyB]

probably flywheel chatter if its not a stock-design flywheel. sometimes cars will develop odd harmonics once a certain amount of weight is removed from reciprocating transmission parts like a flywheel...this causes the pressure plate and other parts to rattle. the cams might be making it worse by causing the engine to idle rougher than it normally would.

i'd keep driving it and ignore it. a bad TOB will slowly go from a rattle to a squeal that you can't mistake, once it gets to the point that its going to die.