Strong vibrations from mid/rear end

[gotboost2jz]

I have noticed two different vibrations on my S14. First, whenever I pass 3000rpm's it get a fast, strong, and loud vibration that I can feel. This happens when either accelerating or decelerating past 3k. I also randomly get a rather strong, very loud, slower vibration when i put the car in the neutral. It happens a lot when I come to a stop or when I slow down to make turns. It's in both neutral or very low rpm's.

I'm going to rotate the driveshaft tomorrow to see if that fixes anything but outside that I dont know where to look. I was thinking maybe it was due to imbalanced wheels but that wouldnt cause a violent vibration when im sitting still. Suggestions?

[Tantwoforty]

i would have to say driveshaft, or tires... i had a flatspot on my tire and it was shimmying alot.. idk

[gotboost2jz]

looked/looking into those two area. Any other ideas?

[S14_Kouki]

I was going to say tires/fucked rim. But for sitting still the driveshaft could be out of balance or loose tranny mount??