Ok when i first got my car , there was a deep sound and a little vibration at about 70-80mph .The sound was really constant with my rpm.At low rpm i can hear the kind off *vroum*sound maybe every 2 sec and as far as my rpm goes up , the noise begin to be quicker ,every 1 sec or less.

I ve change my 3.42 fo 3.73 and now i can here the sound a little louder and the little vibration begin at about 55-60mph.

And by the way i can feel and hear the sound and vibration more when im in 6th gear.

Could it be that my steel driveshaft is not well balanced after 130k?

What would be my option?

Or is it something else?

Thank