My 2004 xterra xe rwd 3.3l V-6 started making a loud buzzing noise when I go over 40mph or above. If I drop down below that is stops but its been slipping in second for awhile and I also smelled a burning smell for a moment. My friend says it's the trani and I was just wondering if anyone could help point me in the right direction of what it could be. Anyone else have this issue or know what it could be? Any advice or help is greatly appreciated.