Step 1: Halfway through Claire's Episode 3 you will come to the sewers after escaping a burning building. Shortly after entering the sewers you can climb up a wall (it has a yellow ledge, you will walk right towards it while going through the sewers). After climbing up you can see a crate. Pick it up and drop it down the ledge. Now complete the Chapter! It's important that you complete the chapter to make the crate spawn in Barry's campaign!

Step 2: In the beginning of Barry's Episode 3 you will start in the sewers. Go to where you dropped the crate earlier with Moira. Pick up the crate and climb the wall on the opposite side. On top you will find an upgrade part. Collecting it will unlock the trophy / achievement.