https://www.tecno2.it/cms/downloads/...ioni-1960-1973
This scanned document (no searchable text included but I might be able to create something from if some software I have does not object to Italian) has reference to a 48DCO3 being available for a Maserati 250F.
See page 24.
I may have missed earlier references as I scanned.
So there may be more to be discovered here to provide dating guidance.
Other than in the file name I have not spotted any dates for availability. The Document appears to be a combination of several product lists of different years between 1960 and 1973.
Wikipedia does not have much either.
There may be other sources ...