Exhaust vibration and rough idle? Ideas

Hello, I have an 05 cummins and it has been giving a puff of white smoke on start up every once in awhile, will run a little rough for a second or two and then clear up and is fine. The idle always sounds like it has sort of a tick to me. But recently I have noticed there is a lot of high speed vibration moving the entire exhuast you can see it from the downpipe to the tip, along with the trans dipstick when idleing. I know its a diesel but I believe there is an issue with it and I am not sure where to start any ideas would sure be appreciated. Thanks