Had my new Mustang GT 5spd. for a couple weeks. It has 300+ miles on it. I noticed when I first got it that when the rpm's reach around 3000 when accelerating (median or light, doesn't matter) in any gear there is a rattle or vibration sound like a bad bearing or something it the tranny or its linkage. I stopped at the dealer yesterday and drove another new GT and it did the same thing but didn't seem quite as loud. If I'm driving at 3000 rpm and hold it (2nd or 3rd) the sound continues until I lift on the gas and when I get back on the gas it is back. Anyone else here notice the same thing and/or know what the cause might be ?