Help!!!!

360ci with a 727 on it 8 3/4 rear end when driving around 60 mph or so i start to feel a pulsing vibration underneath the car. . . people have told me it could be my driveshaft. . could this be true? and wat can be done about it?? also just last week my tranny started making a whining noise once i hit second gear and it gradually gets louder need to fix fast because i dont have another car to drive at the time do i just need to change fluid or something else?