i just purchased a 05 SRT6 and when you start off there is a noise like something is hitting the floor board it's gets louder but at about 45. Mph it goes zaway. If you hit the accelerator passing a car it does it ago but gradually stops. I ordered a transmission mount to see if that is the issue. Today I barely pulled out and you can hear this click click clicking sound so that tells me it's in the transmission or driveshaft. Any suggestions. It has 197k miles.