On my 1989 Firebird Formula, I have had this rattling sound for a while now. I found it comes from the right side of the car. I can feel the vibration where the center console meet the carpet on the passenger side right near the seat belt. what lines or cable run near the center console under the car that might cause that rattling?

 

The ebrake cable is there , but more likely its something from the exhaust like the mount for the cat or something. If its more subtle than that, could be coins in the console. Some cars I pulled had pounds of nickels and dimes in the console.

 

it is definitely on the outside under the car. I have heard it for a while but head slowly progressed since then. I will run the car on ramps and see if I can find anything in that area.

 

If its outside, it can only be an exhaust part or cable or hard line that has come loose. Should be easy to see what's doing it.

 

come to think about it it may be the transmission mount. it has never been replaced on this car so maybe it is about time. that would explain the rattle in the location where is it coming from

 

I would think a loose mount would cause more of a banging or knocking. Rattling implies a more constant noise at certain harmonic, mounts generally just thump or bang when force is applied. If you stand by the description of "rattle", its prob your exhaust.