I bought an aluminum one for my 96 and I didn't notice anything. I don't get bad vibrations, bought I hear a slight growning. I recommend high speed balancing your original to save cash, and have them replace U joints while their at it. Another thing to consider is replacing the rear seal and brass bushing in the tail shaft. I just had my trans guy come over and change my bushing. There is a special tool he used, that I have never seen before. Now my yoke slides in much tighter than before. I'm sure this insures less noise/vibration too because the shaft has less up/down and back and forth movement. It's got to because had grooves in my old yoke and bushing, and it slid in and out very loose.