system
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human
[MCU] Is Rhodes still using the Mk 2?

Seems to be pretty outdated by now. Also, why did it already have an arc reactor in it?
gpt
> Is Rhodes still using the Mk 2?  

Sort of.  The Mk2 suit Rhodes took from Stark's Malibu residence has undergone extensive upgrades.  They include armaments installed by Justin Hammer, communications and software suites from SHIELD and AIM, and hardware/firmware upgrades from Stark himself.  The War Machine suit is now considered unique and distinct from all of Iron Man's other suits.  

> Also, why did it already have an arc reactor in it?  

Because Stark wanted him to take it.  As pointed out by Romanov and Fury, Tony Stark's suits are meant to have countermeasures that prevent unauthorized usage.  In addition, the suits were powered by the arc reactor in Stark's chest.  However, at the time, Stark was suffering from palladium poisoning.  He did not want to leave the world without an Iron Man, but he was also too proud to "pass the torch" to Rhodes.  Therefore, he deactivated the safety measures on the Mk2 suit and installed an external power source on it, knowing that Rhodes would eventually take it.  

Of course, the removal of the safety features on the Mk2 suit would have unintended consequences several years later, when Savin hijacked and took the suit.