The 1st Battalion, 24th Infantry Regiment was assigned to the 1st Brigade, 25th Infantry Division "Lightning" , and served in Iraq from October 2004 to October 2005. The battalion came home with 5 Silver Stars, 31 Bronze Stars, and 181 Purple Hearts and played a crucial role in the Battle of Mosul . During that battle, the battalion saw some of the heaviest, sustained fighting of the insurgency to date. The unit was also awarded with the Valorous Unit Award as being part of the 1st Brigade, 25th Infantry Division . The unit reflagged as the 3rd Squadron, 2nd Stryker Cavalry Regiment and moved to Vilseck, Germany. The 1st Battalion, 24th Infantry Regiment replaced the 2nd Battalion, 1st Infantry Regiment of the now decommissioned 172nd Stryker Brigade Combat Team as of 14 December 2006, In 2008-2009, 1-24 Infantry deployed to the Diyala Province, Iraq to FOB Warhorse and later to FOB Grizzly. In contrast to their previous deployment involving the Battle of Mosul, 1-24 sustained very few casualties, none of which came from sustained engagement with enemy forces. For their reconstruction and humanitarian efforts during this tour, the unit was awarded the Meritorious Unit Citation along with sister units in the 1st Brigade, 25th Infantry Division "Lightning".
Question: How many years after being assigned to 1-25 before 1-24 would replace 2-1?
Answer: 2