Salvatore Montagna was shot in Charlemagne on Nov. 24, 2011.
Police believe he was involved in a power struggle in the Mob.
Quebec provincial police say two men were arrested late Wednesday and are expected to be arraigned today.
Steven Fracas, 29, and Steven D'Addario, 36, both of Montreal, were arrested at their respective homes.
They face charges of first-degree murder and conspiracy to commit murder.
Six other men already face charges stemming from the killing of the former Bonanno crime family boss, dubbed "Sal the Iron Worker" by U.S. authorities.
The accused include Raynald Desjardins, a former Rizzuto lieutenant whose name has come up frequently at Quebec's corruption inquiry.
Provincial police say the investigation and arrests in the case were conducted in conjunction with the RCMP. The two forces often work together in organized-crime cases.