Here's my issue,

My 350z rear wheels are shaking and my car is sometimes fishtailing.

Added new:
Tires
control arms
Brakes

Getting alignment tomorrow to see if that's the problem.

Btw, while the car is jacked mid-air the rear tires are moving and it can't be the bearing.

It's a 350z 2007 Nismo

Here's my issue,

My 350z rear wheels are shaking and my car is sometimes fishtailing.

Added new:
Tires
control arms
Brakes

Getting alignment tomorrow to see if that's the problem.

Btw, while the car is jacked mid-air the rear tires are moving and it can't be the bearing.

 

Why can't it be the bearing?

 

Is this happening on the freeway? If so, you are probably tramlining.

 

The left-rear is shaking also and they both been replaced

 

Bushings or bearings. It's all you've got left.

 

Tell me you're not running spacers...please.

 

take off the wheels and see if its the bearing or bushings. also, if you have aftermarket wheels make sure you have a hub ring to center the wheel and prevent movement. if you have slip on spacers make sure you have extended studs and good spacers (no universal crap, and make sure they fit your hub size correctly). if you have bolt on spacers make sure they are torqued correctly and they fit the hubs correctly.

as a matter of fact...check ALL bolts and nuts in the rear to make sure all are torqued correctly. if you cant find the problem take it to someone who can.