Catalina Number of Boat

In regard to Catalina 27s. There were many made and I was curious to see if there was a way to discover what number my boat was. It was built in 1975 so I assume it would be a low number. Does anybody know if the hull has a sequential number that would indicate which number boat it is. Is it part of the Hull Number. I understand the last two are the year (75 in my case).

Thanks for responding in advance.