'i just started getting a vibration as well, but mine is in the range from 62-78 mph. and only happens when in 6th gear. if i take it out of gear, or put it in another gear the vibration is gone. ive tried the same rpms in each gear, and it never shows up. only when in 6th and under steady pedal. anybody have any ideas?'
I am having the EXACT same issue with my 2009 r/t 6 speed. Only in sixth. It is at the dealership now. At first they thought it was the exhaust, now they ordered a new driveshaft thinking that is the problem. Did you ever figure out your problem?