Back in 1971 the California Highway Patrol printed up a book all about how serial numbers on motorcycles should look. They went into all the current information on Odd even numbering, Transmission numbers, Lower tree numbers, Frame numbers, ETC. This book covered most every brand of motorcycles on the market.
One day a copy of this book fell into the hands of one of the Satan's Slaves. (Honestly I don't know how he got it. It probably fell outta that cruiser when the Chippy went in for coffee. ) He added an illustration to the cover, went through the book a white outed any reference to California and wrote in state and copied the book to sell.
I have a pdf file of that 48 page book on my website if you would like to read or copy it. Harley information starts on page 10. Be sure you read the glossary of biker terminology on the last two pages.