The ARVN Predator is the Ranger's light attack vehicle. It's excellent for hunting down infantry, because the Vietcong have no infantry that hard-counter it, and both it's weapons do gun damage. It's especially good at hunting down snipers, as it is completely immune to their rifle and it's faster than they are.
The full stats for the Predator as of the latest internal builds can always be found on the wiki.
Vietcong Chameleon ZSU
The Vietcong Chameleon is a workhorse vehicle for the Vietcong, because it's capable of tackling a wide variety of enemies. It hard-counters light armour and aircraft, and soft-counters infantry and heavy armour, meaning it's good against everything except defenses. Unfortunately, it's base damage is fairly low, which also reduces it's soft-counter potential considerably, and it's hardcountered by the ARVN's omnipresent Beagles. Best used in groups.
Like the Predator, you can find the stats for the ZSU here on the wiki.