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
An attack on the equestrian courts was inevitable. Every one in the government party who was still alive to the fact that governing implies not merely rights but also duties, every one in fact who still felt any nobler or prouder ambition within him, could not but rise in revolt against this oppressive and disgraceful political control, which precluded any possibility of upright administration. The scandalous condemnation of Rutilius Rufus seemed a summons to begin the attack at once, and Marcus Livius Drusus, who was tribune of the people in 663, regarded that summons as specially addressed to himself.
Son of the man of the same name, who thirty years before had primarily caused the overthrow of Gaius Gracchus(11) and had afterwards made himself a name as an officer by the subjugation of the Scordisci,(12) Drusus was, like his father, of strictly conservative views, and had already given practical proof that such were his sentiments in the insurrection of Saturninus.
11. Cf. IV. IV. Rival Demagogism of the Senate. The Livian Laws
12. Cf. IV. V. And Reach the Danube
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/4-06-marius-revolution-drusus-reform.asp?pg=42