Wondering where the eras are? Can't find V1? That's because it has not been released yet .
It could fill a field artillery role, compared with the heavy role of the SPHA-T.
SPHA-T is Self Propelled Heavy Artillery-Turbolaser SPMAT is Self Propelled Medium Artillery-TurbolaserRAG is Republic Artillery GunIf you look at the affiliation for the SPMA-T, you see that galactic republic is not listed, because the game is the only appearance. (http://starwars.wikia.com/wiki/Self-Propelled_Medium_Artillery)So, we choose between the RAG and the SPHA-T. SPHA-T is the obvious choice, because it appears in many places and was obviously in widespread use (http://starwars.wikia.com/wiki/Self-Propelled_Heavy_Artillery). The only appearances for the RAG are references related to the Clone Wars TV series (http://starwars.wikia.com/wiki/Republic_Artillery_Gun) So: we use the SPHA-T