Hello, and thank you for allowing me the opportunity to help you. If I am not online when you are, please allow me time to return. Is there a serious vibration that occurs with the noise?
no, you can feel it , but the noise is more pronounced
Can you tell me if the vehicle has stock suspension and the stock size wheels and tires?
As far as I know yes it is stock. the vehicle has a trailer package as well
Okay. You need to start by having the rear shocks removed from the vehicle to see if they still have resistance in them. Most shops will visually check them but not remove them. If either of them are not tight then this will occur. If the shocks are fine then the rear transmission mount needs to be checked.
OK I will have this done. In your opion is there any other area that could cause this effect? There is one other thing that I did not mention, Last fall I hauled a tractor and when I pulled it off the trailer the tractor caught on the off ramp and I pulled the sub and trailor backwards a coulple of feet, the sub was in park and the tires move freely backwards.