The transmission fluid dipstick on a 2000 Ford Mustang V6 is located on the driver's side of the engine compartment. It's usually a long, thin dipstick with a handle, similar to the engine oil dipstick but often marked with "ATF" (Automatic Transmission Fluid). Look closely near the firewall on the driver's side; it might be tucked between components. There isn't a single, universally easy-to-spot location, so careful observation is key.
Important Note: Adding transmission fluid is generally only necessary if the fluid level is low. Before adding any fluid, check your owner's manual for the correct procedure and type of ATF fluid to use. Adding too much fluid can be just as harmful as having too little. If you're unsure, it's best to consult a mechanic.