I don't know about the rest of you guys, but I do not like watching some bumblefuck wander around in a YouTube video demanding that I like and subscribe when a simple JPG of the map will do perfectly fine. I could not find any really good maps because everyone wants to do their web 2.0 "interactive app" crap with JavaScript hotspots instead of just putting a plain old dot on the map, so I took the base images and made a set of my own.
In total there are 60 diaries, 22 sniper nests, 20 cards, 15 weapon parts, and 8 longshots. Diaries and cards will always be where they are marked with no exceptions. Longshot targets never move so it does not matter if the entire rest of the map is alerted, if you miss or hit him several times, etc.
Also required for this achievement are completing all of the optional objectives in each mission. I always completed/discovered these by accident while simply completing the primary objectives and searching out collectibles, so you should not have much difficulty getting those done in the course of chasing collectibles around.
Weapon parts are all found by looting enemies, but fortunately, the same enemy always holds these parts. Some enemies are stationary and some are mobile, but their locations will only mean anything if the area is not alerted to you. Once they start dashing around, hiding, and attacking, all bets are off. Fuck knows where your weapon part went.
Rings indicate that there is more information, so read on below the image if you need help.
Mission 1 - Siege of Tobruk
Mission 2 - Gaberoun *** Spoiler - click to reveal ***Cards: 1
Diaries: 11 Both weapon parts are held by soldiers that wander. The western weapon part is held by a sniper up on the ridge, and the northern weapon part is held by the only guy wearing a white tank top.
Mission 3 - Halfaya Pass
Mission 4 - Fort Rifugio
Mission 5 - Siwa Oasis *** Spoiler - click to reveal ***Cards: 1
Diaries: 9 The southern weapon part is held by an officer who wanders around the anti-air gun. The northern weapon part is held by a sniper on the roof of the marked building. To get to the sniper, you must go just to the west of the building and you'll find a ladder to climb.
One of your primary objectives will be to climb some scaffolding where you will witness a meeting between three officers. One of these officers is your target that you must identify and follow. Your target will go to one of several buildings on the map to retrieve what is identified by these officers as Vahlen's journal. This journal he collects is your collectible diary. You cannot kill any of these three officers until the target officer collects this journal because the mission instantly fails if you try it.
Mission 6 - Kasserine Pass *** Spoiler - click to reveal ***Cards: 3
Diaries: 8 Like above, the last diary in this map is a primary objective. You must get a safe combination from an officer which is required to complete the mission. This safe combination is your collectible diary.
The weapon part in the eastern ring is held by one of the soldiers originally inside this building at the start of the level. When heading into the building, it should be the guy furthest to your right.
Mission 7 - Pont Du Fahs Airfield *** Spoiler - click to reveal ***Cards: 3
Diaries: 9 Your second weapon part is at the very end of the mission. After covering your friendly jeep as it rips up and down the airstrip, a lone enemy sniper will appear in the general area marked by the ring. He will often go into the watchtower at the south center of the ring, but not always.
Mission 8 - Ratte Factory *** Spoiler - click to reveal ***Cards: 5
Diaries: 5 This mission has two distinct elevations and it's difficult to figure out what you need to find. The last objective on the top story of the factory is to place a satchel charge to blow something up. A group of enemies will appear below you and another group ahead of you from an elevator. This elevator takes you down to the next part at the canyon floor and you cannot traverse back. It has a large radius where it assumes you're ready to go so just steer clear of it until you're done up here.
On the top floor of the factory where you start, you will find 3 diaries, 2 sniper nests, 3 cards, 1 weapon part, and the level's longshot. The weapon part is in the possession of one of the guys in the northern ring. They're all identical and I always get spotted trying to be sneaky, so just Panzershreck them and sift through the bodies later.
On the bottom floor of the level, you will find the remaining 2 diaries, 1 sniper nest. 2 cards, and the game's last weapon part. As soon as you hit bottom in the elevator, use your binoculars to look at the top of the huge Ratte tank at the middle of the room. A standard infantryman will be walking off the left side of the tank and down some ramps to the ground level. This guy has your weapon part. As for the last sniper nest, it is directly at the end of the level where it directs you to stand to destroy the tank.
The original source of the plain map images is apparently gryonline.pl. I lifted them from GamePressure.