I have read about the serial numbers on Camco LA 1973-1978. I know that 

Camco didn't have serial numbers in the Chanute or Oaklwan era. But the LA Camcos have serials

and I have seen photos that there are numbers on LA mostly on the re-rings. I have a LA kit Camco and there's no number inside the shells. I have read somewhere that not all LA kits have serials.

Is there any other that have seen LA kits without serials?