I thought the official Arrma parts list might be useful here. I find it quite helpful in trying to compare where a part is used on multiple models. With some of the Arrma forums lacking information, or just getting started like this one, it often helps to be able to expand your research to other models and know how they relate to the one you own.
www.arrma-rc.com/pdf/xref/arrma-parts-xref-A.pdf
www.arrma-rc.com/pdf/xref/arrma-parts-xref-A.pdf