DPRK Gunship-transport (Three of Hearts) - This unit is linked to the Three of Hearts; once you incapacitate him, this unit will not appear anymore. You may consider leaving the Three of Hearts last and verify him right before the Ace of Hearts contract. Go north of the Kusong MASH to the Sinuiju Farms. He will be on the field with several tanks and gunships. By far the easier of the pre-set choppers to hijack.
DPRK Gunship-transport (Seven of Hearts) - This unit is linked to the Seven of Hearts; once you incapacitate him, this unit will not appear anymore. You may consider leaving the Seven of Hearts last and verify him right before the Ace of Hearts contract. Go north of Yongbyon Station and head directly east of the Industrial Zone to the Seven of Hearts. A gunship is sitting next to him; simply head into the area from the south and hijack the gunship. Repair it for free by cancelling any contract and opting not to retry.
DPRK Gunship-transport (Hearts, Spades) - East of Changsong Train Station, there is an eliptical road. Go to the east section of the loop and look for an alarm tower east of the road. One of the gunships can be seen; nearing it will cause the SNS Radar to be jammed. Go up the slope and take any of the gunships there.
DPRK Transport Chopper (Hearts, Spades) - Locate the eliptical road near Changsong Train Station and drive along the north section. North of that road, near the restricted red area, is a small airbase with a transport chopper, a tunnel, and a tank.
DPRK Scout Chopper (Hearts, Spades) - Between Taechon Battlefields and the dirt road immediately east of Taechon, there are two small airbases with Scout Choppers on their pads. You're required to hike up to those bases
DPRK Scout Chopper (Spades) - East of Farm Valley, a small base is nestled in an equally small valley. Several ZSU and SAM carriers are around, as well as a tank. Probably too much work for a simple scout chopper.
DPRK Type 62 Tank (Hearts, Spades) - Near the North Korean garrison on the southeast, there are several tanks patrolling the area. If you want a tank for infiltration, snag one here or near the Taechon Reactor in the west. If you simply want firepower, stick with a Chinese Type 96 tank.
AN Gunship (Hearts, Spades) - This requires a sniper rifle or anti-material rifle and the ability to lose $25,000. Head to the east entrance of the Kusong MASH and climb the local hillside. This places your merc at the height of the choppers, allowing a clean kill through the chopper canopy. It will take patience for you to line up the perfect shot; the sniper rifle's bullets will only penetrate the canopy (and hit the pilot's head) from the side (the front is armored).Snipe the pilot (you may want to hang back and let the mountain block the line of sight of AN troops) and the resulting "accident" usually results in the gunship being in barely serviceable condition. The act of killing an AN pilot will also deduct $25,000 from your current funds. Faction status is only reduced if another AN soldier or manned vehicle witnesses your act of aggression. From there, you may repair the gunship and take your new ride for a spin. Note that if you miss and strike the aircraft, the AN pilot will most likely turn and fire on your merc, killing him or her instantly.
Russian Coaxial Gunship (2nd Russian Mission, Spades) - During one of the Russian missions in the Spades tier, a Kamov coaxial gunship is available in the North Korean Village north of the Industrial Zone. You can only get this gunship once per game (unless you decide to keep that contract around so you can get that vehicle). It is weaker than the DPRK gunship and cannot carry passengers, but carries more anti-tank missiles and uses cannons instead of machineguns. It is definitely more manueverable and smaller than the AN gunship (which is fairly small to begin with).
Russian SUV (Hearts, Spades) - This is the $ symbol vehicle in Yongbyon, south of the Russian HQ. If you need to enter the Mafia Outpost for exploration, try grabbing this constantly respawning vehicle.
Chinese Type 95 AA Tank (Spades) - The Chinese base of Dandong has at least three of these babies in their base. Once the Dandong bridge is destroyed however, the ability to move these units anywhere is impossible, except through the Russian Mafia shop.
Chinese Type 96 Tank (Hearts, Spades) - Near the Chinese base at Dondang. At least two of them are available near the bridgehead leading to the Chinese HQ. Later on, several will be patrolling the Dandong base. Once the Dandong bridge is destroyed, this unit is still available since it is at the bridge head. Some may be fighting the ROK or DPRK forces down near the Sinuiju, Taechon, and Chongju areas; hijack one if you need them.
Chinese Transport Chopper (2nd ROK Contract, Spades) - An S70 Chinese slick will be available on the hill overlooking the HQ at Dandong. It is probably a getaway vehicle for mercs who head into the Chinese held area on the ground; nevertheless, you can hijack it easily during this mission.