Below you will see an almost complete paper-strength US Army Rifle Platoon for the Vietnam period. Although I only have two rather than three platoons of basic infantry, this is enough to give me plenty of units if configured for a more realistic "in country" strength.
All the infantry figures are from the now seemingly defunct Flashpoint range, although I think the chap who designed them is responsible for the new Battlefront/FOW "When We Were Soldiers" range. The Pattons, M577, M113s, Duster and M551s are from Battlefront.
Company HQ & Specialists
company hq
weaponsplatoon
sniper
Core Troops
1st Platoon
1st platoon/weapons squad
2nd platoon
2nd platoon/weapons squad
Support Troops
M577 Command Vehicle
M113 APCs
M551 Sheridan Tanks
M41 A3 Walker Bulldog Tanks
M48 A3 Patton Tanks
M42 A1 'Duster'
Aerial Assets
Half AN AIRLIFT plAtoon
Riverine Assets
Monitor C&C Ship
Monitor
Monitor APC
PBR
PACV Hovercraft