Quick look through the d20 books.. if you were to stat the Marines for Starcraft.. I'd use either the low to mid level thugs (d20 Modern core pg 273-274) as freshly 'conscripted' to those who've served part of their term. Give them the Powered Armour feat for free (for the low level thug) and remove one of the mid level thug feats to compensate for the free feat.
For career soldiers, use the Swat ordinary d20 Menance pg120, and just switch out feats where necessarily. These would be the squad leaders, or more 'elite groups'.
Then for firebats and marauders can add a level or two at most (in whatever class) as they're generally 'better' units, not just due to their equipment.
I'll be putting up the Clone Troopers (Jango Fett Genode/Clones) at some point soon.. with basic trooper, then some kind of training packages/changes for those trained for different stuff (winter troopers, flame troopers, jetpack, etc) and ARCs and leaders.
For career soldiers, use the Swat ordinary d20 Menance pg120, and just switch out feats where necessarily. These would be the squad leaders, or more 'elite groups'.
Then for firebats and marauders can add a level or two at most (in whatever class) as they're generally 'better' units, not just due to their equipment.
I'll be putting up the Clone Troopers (Jango Fett Genode/Clones) at some point soon.. with basic trooper, then some kind of training packages/changes for those trained for different stuff (winter troopers, flame troopers, jetpack, etc) and ARCs and leaders.