Thank you for your email. As per how we do/did our serial numbers you have a 1977 Marinoni frame on your hands. Back then the first two digits were the year, think they only did it that way in the '70's - since the 80's and 90's the first digit is the year and the rest of the numbers are the number made in that fiscal year. Since the year 2000's we put a letter first then digits. only in the 70's (started making in '75 or '76 but only a few the first years) did they do the year as the first two digits, then the remaining numbers are the sequence made in that year.0123 (as an example) is the 123rd frame built for the 1980 fiscal year, 1123 same thing for 1981 etc.00123 would be the 123rd frame built for 1990 (5 digit's for the '90's normally - as we built over 1000 bikes some years in the 80's it could be 5 digits but great detective works shows me if an 80's or 90's bike. A for 2000, B for 2001 etc, we're at Z for 2022 (we skip letter that look like digits) An overload of info probably, but was to explain how we did them, sorry to say I have very little order forms back to scan for our files, so can't offer any further information beyond that and your bike itself, thanks! Kind regards, Julie ;o)