This is the beta version of a sides mod I whipped up a few years ago, it will mess with online compatibility since it overrides mission scripts, but you do not need to back up your rep.lvl and repshell.lvl for this mod (but it's a good habit, trust me)

New weapons/skins for the Republic. Takes effect on Coruscant, Felucia, Kamino, Kashyyyk, Mygeeto, Naboo, Utapau & Yavin IV.

BARC Speeder and Republic Tank get new skins as well.

*Felucia and Kashyyyk feature the Phase 1 ARC skin for the sniper

The 1.0 Version of this mod is more comprehensive but I can't find it, if I do I will upload.

Readme

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Screenshots

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Download Link
http://www.moddb.com/games/star-wars-battlefront-ii/downloads/501st-clone-legion-mod