Q: My car is shaking - 2000 Ford Mustang

If the shaking is occurring with the car stationary, that would not involve the wheels or driveshaft, although it could implicate the torque converter. A shaking engine diagnostic would start with the motor mounts. If those are judged solid (there are tests), one should assess the mechanical condition of the engine by checking cylinder compression.

The reason for that is if cylinder compression varies too much, that variance alone can account for this symptom. If the cylinder compression is too low or varies too much from high reading cylinder to low reading cylinder, one would then try to rule out easily repairable items like a mispositioned timing belt or chain. Of course, if compression issues are traced to valve train problems, the heads have to be serviced.

Other potential causes of the vibration are a broken harmonic balancer, engine ignition timing being off, and flexplate and/or torque converter damage or imbalance. Prior to getting involved with diagnosing an imbalance in something as hidden as the torque converter, though, the engine should be put on a scope to determine if there is something going on in individual cylinder firing conditions that would account for the vibration. Varying power output from individual cylinders, due to possible fuel and ignition system problems, obviously will cause vibration: you could have a bad coil, plug, injector, and so forth. A scope makes that diagnostic easy.

I recommend having a certified mechanic, such as one from YourMechanic, come to your location to determine why the engine is shaking and suggest any necessary repairs.