After the Battle of Hoover Dam the NCR did not run down the rest of the legion but strengthened there position in the Mojave. They sent scouts to watch and follow the "runners of the legion". NCR and MR house made a deal that would allow The NCR to control the damn but no NCR Soldiers were allowed into the strip, Except for when they want to drink and gamble. Mr House sent some of his Troops to the Hoover Damn to insure its security of the dam if the NCR were to be attacked.
2 years later the NCR scouts reported that a legion camp was under attack and realised that the Legion was having leader issues and the legion was split into two small factions that went at war with each other . Around this time the NCR had approved the "Power Armour Program" This allowing the Powered armour into service. recalling around 70% of the Salved power armour and rebuilding them up to work with Fusion cores. The issue was that The NCR needed alot of Fusion cores for the armour to work. Mr House was able to design a Converter for the dam, This allowed this Converter to use the dams electricity and Produce "Fusion Cores", However these cores were weaker than the Fusion Cores. They renamed the cores to Electro Cores. Even know these were weaker they could produce a lot more cores and keep the units up and running. Mr house did ask for a price of 20K Bottle caps a month for them using this Converter.
The Troop tree would be slightly changed,The individual could become a recruit for the power armour program but they would would wear the salvaged Power armour. Then when The individual gets promoted they will get the powered armour.
and If an individual are already in the NCR has a Trooper you could enlist to the Program. Depending on the rank the trooper who enlisted could go straight into the powered armour instead of the salved Armour.
The NCR spent a year getting they Heavy units trained and prepared before sending them up to the war of the "Running Legions Tribes". A year after the scouts reported that the legion had split up all veteran rangers and some rangers were relocated to another Campaign. The Powered units were very effective at neutralising the Legion tribes.
The NCR would keep these units in service for many years to come.