SR Tranny Issue

[fliprayzin240sx]

K im starting to get hella paranoid bout this. My tranny/shifter would vibrate like nuts when i get to round 90mph. It kinda went away after i changed tranny fluid, but now its back, not as bad as before but its back. well last nite all of a sudden im driving home, cruising bout 75-80 mph when all of a sudden the whirring noise that you usually hear from the tranny kinda got louder, loud enough that i can hear it with my sunroof open and music playing. It also got this sound like a freakin heatshield is loose or something. I double checked everything that i can today and didnt see anything. Tranny bolts are all there, tranny fluids not leaking, mount bolts are all there...any suggestion? Tranny shifts smooth and everything, theres the usual metal shavings on the tranny drain plug when i changed fluid.