Mission 3: Old Wounds
Intel Item 1
Near the beginning of the mission, you will enter a cave and have a cutscene briefing. Once the scene is over and you are back in control, look to the end you will see it on a crate against the wall.
Intel Item 2
When you leave the first cave after the cut scene and grabbing the first intel item, you will hop on a horse and need to ride out into the desert to the next objective. Instead, ride straight out from the base until you come to a large set of rocks with a red flag at the base standing in some tires. The intel will be on the ground beside the flag. Look well though, as it can be tough to spot.
Intel Item 3
Once you are riding out to the weapons caches, you will come to the second one that is on a Cliffside with a few wooden bridges to the left and right of it. Walk along the path from the cache to the right and cross the wooden bridge. Once on the other side, go to the right and you will find the intel on the ground, leaning up against the wall.