If you gonna do metal arms stay away from Integy. Their aluminum is closer to tin foil than anything 6061 or 7075...very poor quality IMHO. Get the GPM ones if you're gonna do it. The GPM ones are kinda the standard for aluminum arms. Vitavon makes some too but not in Kraton/Outcast/Talion length. I wouldn't do aluminum arms on an off road car...especially if you're gonna be bashing and jumping. Aluminum arms are better for on road use. If you still wanna do the arms then invest in some aluminum diff cases (Vitavon, Basherqueen, Treal or Hot Racing make good ones) to match. It's better to go all aluminum. The aluminum arms will tear up composite diff cases on even minimal impact.
But to answer your question...yes the Kraton arms will fit an Outcast 6S. The Kraton, Outcast/Notorius, Fireteam and Talion all use the same arms.
Good luck with whatever you decide and welcome to the Forum!!!