This mod switches all clone models to phase 1 on all vanilla maps, I also re-textured each of them to my liking.
Works everywhere except the unit purchase screen in galactic conquest as well as 1st person (I tried messing with it, but it seems to be impossible to change).
The colors for each class are all made in photoshop/blender by me. They are by no means lore-friendly, but they take designs from actual batallions:

Clone Trooper - 501st, basically took the phase 2 coloration and put it on phase 1 + added blue rims on ankles
Heavy Trooper - this one is the only fully unique one, doesn't correspond to aby batallion
Clone Sharpshooter - commander Gree + a few additions such as kill marks
Clone Engineer - 212th Attack Battalion,specifically phase 2 colors + galactic medic emblem on the chest. Replaced pilot model with regular trooper, because I like the fin
Clone Commander - commander Wolffe, my beloved. I'm very proud of this one, spent a lot of time on it
Jet Trooper - 501st, same as with regular trooper - tried imitating phase 2 variant from the game
Clone Pilot - same as it ever was.. except added some scratches and color corrected a bit (btw did you notice all of them have scratches now??)
Clone Marione - same as Clone Trooper.

-INSTALLATION-
Put rep.lvl into "Star Wars Battlefront II Classic\GameData\data\_lvl_pc\side".
I recommend backing up the original rep.lvl file before overwriting, or don't :)

Hope you enjoy!