rough idle

How bad are the vibrations? Are you seeing any fluctuations in the RPMs? Any lose in the MPG you where getting before? Any other drivability issue, even if they are small? Anything you can give will help narrow the search. Right now it would be a pretty big list if I wrote it out.

every thing is running good, no loss in rpm,suggest motor mount,and a reputable seller

Does the vibration only happen when the engine is cold, or does it continue even when warm?

it is a constant , as if theres a vibrator resting on the entire car,do you think it may be the harmonic balancer, if so how can i test

I do not have info on the harmonic balancer. Does it feel like it misfires when you accellerate? Check Engine light on?

no, As i looked under car i noticed that the transmission mount bushing is split in half. Maybe this is causing the trouble

That could very much do it. When the car is cold, start it up and put your hand on the tranmission mount and see if that is the bulk of the vibration. Regardless, fixing that is likely a good thing, but it's going to be a pain to replace.