I have a 2005 CC Frontier now has 61,000 miles on it and the last week or so has been making a noise that concerns me a lot. I haven't had time due to work and schedule to take it anywere yet. When driving usually around 40 mph it makes a noise sounds like transmission or drive shaft area that rumbles and vibrates the entire truck. When it does this if you let off the gas a little or accelerate a little it stops. Does anyone have any idea on what this might be? I have the "Limited" power train warranty to 100,000 miles so hopefully it will cover what's wrong. Thanks in advance for the help.