UACguy
Unlocks Hell Knight Model
Look for the stack of crates inside the Cargo Station after destroying the Argent Filter in the upper floor of the garage. Use them to reach a maintenance access area above the lights. Look left to find the Collectible, UACguy.
Stealthguy
Unlocks Rocket Launcher Model
Exit via the back of the Cooling Tower and go left. Hop over the gap in the pathway and climb up the shaft to the left. Instead of jumping over the chasm, walk right along the narrow ledge. Hop through an opening on the right and collect the Collectible on a small box ahead.
