TA-02 Rear Arms

[tamiya3speed]

So I bought two of the TA-02 anniversary Porsches and I am considering converting one to regular touring car wheelbase.  From what I understand all I need is new wheels and a set of TA-02 rear arms.  It looks as if the 50556 are a rare find now a days.  Are these the only option outside of aluminum?  Has anyone ever run the aluminum rear arms?  I'm not normally a fan of aluminum arms but it will be mostly parking lot running in big open lots so not too worried about big hits.