Same thing happened to me when i was sent a replacement for one that was faulty out of the box. The numbers should be on a piece of card, about postcard thickness, amongst the other literature that comes in the box. I rang the people who I got the replacement camera from (Holdan, UK suppliers) and they gave me the numbers over the phone.
I registered mine about a week ago. The number can be found under the viewfinder. In my case the cardboard packing box also had a white label with the serial number on it.
Curiously, I needed only the serial number for registration. Mine is of the form BxTDAxxxx, where the x's are numbers.
I had to email to Panasonic Broadcast to get my numbers.
Can´t find the adress right now but I found it somewhere in all the documentation that came with the camera.