Noise after you take your foot off the gas and let the car coast It is rithmatic and slows down as the car does It is not the breaks and if you put the car in nutral while coasting it still makes?

You did not give the year / info on this unit. If this is a rear wheel drive unit I would take a look at the universal joints... If it is a front wheel car, look at the CV joints (front axle u joints)