Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Among the conservatives he belonged to the section of Crassus and Drusus. We do not know what primarily gave occasion to his soliciting the tribuneship of the people for 666, and on its account renouncing his patrician nobility; but he seems to have been by no means rendered a revolutionist through the fact that he, like the whole middle party, had been persecuted as revolutionary by the conservatives, and to have by no means intended an overthrow of the constitution in the sense of Gaius Gracchus.
It would rather seem that, as the only man of note belonging to the party of Crassus and Drusus who had come forth uninjured from the storm of the Varian prosecutions, he felt himself called on to complete the work of Drusus and finally to set aside the still subsisting disabilities of the new burgesses--for which purpose he needed the tribunate. Several acts of his even during his tribuneship are mentioned, which betray the very opposite of demagogic designs.
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/4-07-sulpician-revolution.asp?pg=59