The exact location of a Vespa number will vary depending on the model of your scooter. However, it is usually located somewhere on or near the engine.
On the frame
Frame
The frame
Check the butt or frame.
Look on the frame.
look on the frame
On the frame
On the frame. It's on the steering tube
Frame and/or butt
On the frame
Serial number is on the frame.
mine was on the front of front motor mount