Hey Max,
To figure which one...
1. REAR: To tell if it's the rear mount put the car on ramps where you can get under it. Then using your hands, try moving the motor front to back. If the mount is bad, you'll see the rear mount move back and forward. (the mount it located on the top side of the subframe underneath the car connected to a bracket at the back of the transmission. The mount but it has a rubber isolator on it and shouldn't move.)
1. PASSENGER: For either the passenger or driver's motor mount you can use the rock 'back & forward' test however a more reliable test is to look underneath the motor mount for signs of brownish streaks. The mounts are filled with a hydraulic fluid to absorb vibrations and covered with rubber end caps. When the mount breaks the fluid comes out and leaks down the car. For example, on the driver's side, if a mount breaks, the fluid lands right on the end face of the transmission that's visible if you peel back the driver's wheel liner. If you ever see brown fluid leaks on that face, it's the driver's mount that's failed. With the passenger side look directly under the mount section that has the black rubber on it. Do you see fluid running down? (may be dried if it happened a while ago) If so, the mount needs to be replaced.
I put three videos below which cover the procedure on all of them.
Note, the rear and driver's side mounts attach to the transmission so are the same on both engines. The passenger mount is a different part for the 2.4 and 3.2 engines but the changing process is broadly the same.
- Video #1 is replacement of the passenger side mount in a 3.2 engine
- Video #2 is replacement of all of the mounts in a 2.4 engine (zoom to about 2/3rds the way through to see how he does the rear mount. The ratchet strap process could also help determine if that mount is bad if you can't visually tell.)
- Video #3 is the tip to greatly reduce the amount of time and disassembly if you ever have to do the driver's mount. It involves a drill/Dremel for a small plastic modification on the battery tray that takes 10 minutes but will save a half hour of needless disassembly.
Hope this helps, good luck!