new rear squeak (not rear ball joints)

[THE VEIN]

I already have the rear ball joint squeak on both sides on my car but now I'm starting to notice a new squeak that sounds like it's coming from under the passenger side rear seats. I can only hear the ball joint squeak when I have the windows down, but this new squeak is very loud and I can hear it no matter what. I'm thinking is the subframe bushing but is there any other way I can check if it's the subframe bushing or maybe it's the rear ball joint getting louder

[Ricky Bobby]

Its prob the ball joint getting louder, the rear subframe bushings just clunk and make it feel a bit looser in the rear.

[THE VEIN]

ok cuz like I said sometimes I can hear the noise coming from under the back seats and sometimes I dont

[Ricky Bobby]

How many miles on your stock shocks? Those really can clunk as well.

[FRC Z51]

I also have the same squeak and it's been driving me crazy! It seems to be coming from the rear somewhere. A very faint wobble/squeak type sound. Possibly the slide out shelf? I plan on having a friend ride back there to help figure this out.