If you needed a factory replacement frame the dealer stamped, or should have stamped your old number on it. They would have been made to the specification of current production frames plus the 2 cable brake stops and the mount for the rod brake pedal. So a 4 lug frame could legitimately have CA7, EA7, FA7 or GA7 number prefix
There was a parts service bulletin in 1960 which introduced them. I only have a poor copy (below)
If you have the haynes A10 manual and look at the photos on pages 37, 38 and 54 you will see that the frame is a 4 lug rod brake and cable brake frame.