The Volga
Compass (Upgrade 1)
After almost being eaten by the giant water monster, Duke will pull you out of the water. Head to the plane he mentioned behind him and work your way up towards the cockpit. The upgrade will be between the two pilot chairs.
Extended Filter (Upgrade 2)
Locate a red shipping crate north of the train tracks in the center of the map slightly west of Safe House 5. The upgrade will be located in the very back of the crate.
Ammo Pouches (Upgrade 3)
Locate a fortified structure slightly east of Safe House 5. From the gated entrance of the building, head up the metal stairs. Enter a hole in the wall on the left. Be mindful of the hanging cans used to alert the bandits. Take the stairs on the left down and turn right at the bottom of the stairs. Keep heading straight until you reach the upgrade sitting on a crate on the right side of a room filled with beds.
Throwing Weapons Harness (Upgrade 4)
Head to the gas station on the east side of the central land mass. From the front entrance head into the gas station and look for a locked door. Shoot the lock off the door and head through it to reach a dark room. The upgrade is in the back left of the room on a metal shelf next to a locker.
Reinforced Helmet (Upgrade 5)
From Safe House 6, head southeast towards the water. Cross the water using the submerged tracks to the left of a boat dock. Once on the other side, turn right towards the ruins of a large structure. Head past the blue truck and into a small room on the right side of the structure to find this upgrade.
Battery Charge Controller (Upgrade 6)
From Safe House 4, head south to the small shed past the central structure to find a generator. To start the generator, you will need to retrieve the gas can behind the shed. Once started, head into the central structure and work your way through the building until you locate a person lying on a table who was being electrocuted. The upgrade is located on the body of this person.
Metal Detector (Upgrade 7)
This upgrade is located on the large island in the southeast corner of the map. From the giant cylinder where the teddy bear was, head west until you come across a small shack. The upgrade is located inside on a desk to the left.
Night Vision (Upgrade 8)
Located in the large warehouse to the northeast. To enter the building you will need to find the boat a short ways to the south at a dock and sail to the building through a broken section of the wall accessible via water. After you dock the boat in the building follow the path forward until you reach a set of metal stairs leading to an arched wooden door. You will need the key obtained from saving some cultists at a bandit camp (which was located in the fortified structure with a gate in the northeast slightly east of a safe house where you received the Folded Letter and Ammo Pouches) to unlock the door. The upgrade is located on an altar on the right side of the room.
The Caspian
Motion Scanner (Upgrade 9)
Enter a makeshift stronghold in a giant boat via an entrance on the right (east) side of the road and head straight through slave quarters. Keep working your way through the second level slave quarters. When you reach the end, take a yellow ladder up to reach the deck of the ship with some shipping containers. Head through the doorway straight ahead and take the ladder on the left side of the room to reach a higher ledge in the room (there will be three enemies in this room). Follow the ledge into the next room and keep moving forward. Head up the yellow ladder at the other end of the room and go into the room slightly to the left. The upgrade will be located on a wooden table on the right side of the room.
Extra Bright Flashlight (Upgrade 10)
This upgrade is located in a boat safe house near the rock tunnel entrance to the lighthouse in the northwest corner of the map. When you enter the boat, note that there is a tripwire just before the upgrade. The upgrade is on a crate to the left of the cot.
Armored Glass (Upgrade 11)
Head into the bandit hideout located west of the northernmost safe house via the ravine. Kill all the enemies in the ravine and the rope ladder leading up into the cliff will drop. Climb up this ladder and the upgrade will be to the right on a wooden crate.
NVD Amplifier (Upgrade 12)
Enter the airfield in the southeastern part of the map and head to the main building with a Demon nest attached to the front of it. Work your way all the way up to the top, fighting Humanimals as you go. This upgrade will be located on a chair in the safe house right next to the workbench.
Consumables Carrier (Upgrade 13)
Located north of the airfield safe house in a cave along the water. The cave will be down the slope to the right of a man claiming to be the Baron. The upgrade is to the right of the workbench.