It only makes this noise when driving not in park. this is a sporadic type of noise and some times this will be 3 to 4 times in a row.
I have a popping noise some where in the rear end. It mite be the rear end pinon on 2005 Cadillac Escalade EXT
It could be something simple like a U joint. Even if the joint is not loose, a lack of lubrication inside the joint can cause some nasty noises. The U joint is usually a sealed part from the factory and cannot be lubed. Removal of the driveshaft and inspection of the U joint can usually determine if the joint is bad.