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
In the same spirit Sulla caused consuls to be elected even for 673, through which at least the odious custom of dating officially by the regency was avoided; nevertheless the power still lay exclusively with the regent, and the election was directed so as to fall on secondary personages. But in the following year (674) Sulla revived the ordinary constitution in full efficiency, and administered the state as consul in concert with his comrade in arms Quintus Metellus, retaining the regency, but allowing it for the time to lie dormant. He saw well how dangerous it was for his own very institutions to perpetuate the military dictatorship.
When the new state of things seemed likely to hold its ground and the largest and most important portion of the new arrangements had been completed, although various matters, particularly in colonization, still remained to be done, he allowed the elections for 675 to have free course, declined re-election to the consulship as incompatible with his own ordinances, and at the beginning of 675 resigned the regency, soon after the new consuls Publius Servilius and Appius Claudius had entered on office.
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Reference address : https://www.ellopos.net/elpenor/rome/4-10-sullan-constitution.asp?pg=59