If you want to find the frame and engine numbers of your Bella R204, you can find them in the following places:
On the right hand side of the engine on the top:
On the right hand side of the frame just below the front of the two brackets on top
On the type shield under the seat
On the Cylinder
If you’re wondering what type your Bella is; you can also tell from the engine and frame number (if they match) if your shield is missing from the below table (except for the R204 which starts from 127001: