Heroics and Ros Indochina 1946-54
French Corps expeditionnaire :
1)Most figures are US WWII (USR 1, USR 2) which are mixed with others such :
2) British Paratroops WWII (BR3), as in 1947-50 many of the French Paras wear a similar uniform ;
3) troops in bush hats : Confederate in hats (MACW 6 Confederate infantry skirmishing), remove the blankets rolls and/or try Confederate cavalry on foot figures (MACW 23)
4) Some Modern Insurgents infantry (M21)for Foreign Legion infantry : the cap, with little work, becomes a white Kepi ( this is parade dress, but…)
Viet Minh
Basically , it's a mix of WWII British (BR1, BR2)and Modern GB with "old" helmet (M5, these figures are a little tall, you'll have to think to a "diminutive" basing), add some WWII Japanese(JR1, JR2).
Heroics and Ros Vietnam 1965-1975
Vietnam/Vietcong : same figures as above.
U.S.Army
Most units are covered by Modern US infantry with "old" helmet( M1, M2).
Special Forces may be painted using the "Modern Insurgents" pack (M21).
Australian or other units in bush hats : Confederate as French above.(some Austrian Napoleonic Jaegers an also be of use),
adds a tower to his 15mm trainyard.