Figured throwing this up here would help anyone who might need it for routing or buffer strats. Also figured having this in a place where people will know where to look would be more helpful than having to pull up google every time and hunting for the answers that way.

The contents of each area's E Box is the same every time and will always require the same number of plugs. There's three different kinds of boxes: Green, Red, Yellow. Green will hold only medical supplies, Red will hold only ammunition, while Yellow will contain a mix of both (and are fewer in number compared to Red and Green boxes). While Green and Yellow only require 1 plug each, Red is the most variable of all of them, requiring anywhere from 1 to 3 plugs. The amount of plugs needed for the Red boxes are noted next to their location. Take that into consideration when you're considering what boxes you want to utilize.

I've sorted these boxes in the order in which you would encounter them during your run:

Green: Control Room Hall Hemostat x 2 Med. Pack M x 2 Rec. Aid x 2 Resuscitation x 2

Red: Elevator Hall (2 plugs) 9mm Parabellum x 34 SG Bullets x 10 Poison Dart Intensifier

Yellow: Strategy Room Med Pack M Hemostat Intensifier Slag Bullets x 5 Resuscitation

Red: Main Hallway B1 (2 plugs) 40S&W Bullets x 15 Slag Bullets x 10 SG Bullets x 10 Poison Dart

Green: Research Area Hall Recovery Aid Intensifier x 2 Resuscitation x 2

Red: Communication Room (1 plug) 9mm Parabellum x 17 SG Bullets x 10 An. Aid Multiplier

Yellow: Control Room B3 Hemostat x 2 An. Aid x 2 Multiplier Resuscitation

Red: Control Room B3 (3 plugs) Grenade Bullets x 3 Heat Bullets x 3 SG Bullets x 5 An. Aid Intensifier

Red: Experiment Room Hall (2 plugs) Poison Dart Slag Bullets x 10 40S&W Bullets x 15 An. Aid Multiplier

Green: Experiment Room Hall Resuscitation Recovery Aid Intensifier Med. Pack M x 2 Hemostat x 2

Red: Central Stairway(3 plugs) Poison Dart Heat Bullets x 3 Intensifier x 2 Multiplier An. Aid x 2

Green: Central Stairway Hemostat Intensifier Recovery Aid x 2 Resuscitation

Red: Power Frequency Room (2 plugs) Heat Bullets x 3 Grenade Bullets x 3 Slag Bullets x 10 An. Aid x 3 Intensifier

Green: Power Frequency Room Resuscitation Recovery Aid x 4

Hovercraft Slag Bullets x 10 Recovery Aid

Red: Hovercraft Storage (1 plug) Intensifier Multiplier An. Aid

Yellow: Underground Heliport Med. Pack M x 2 An. Aid Recovery Aid Resuscitation

Hope this helps anyone who might need it! :D Maybe one of these days when I do a routing session of my own, I'll map out where all the random item drops are.

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UPDATE: I went ahead while I was mapping out item drop locations and went through the trouble of finding all the plug drops. You can find them in the following rooms:

Management Office (same shelf as DDK H) Elevator Hall Lecture Room Hallway (on body) Backup Generator Room B1 (behind shelf) Strategy Room Large Size Elevator (on top of crate) Computer Room Research Meeting Room Control Room B3 (behind movable shelf) Rest Station (on corpse) Central Stairway Researcher Rest Room (on bookshelf) Disembarkation Immigration Room (on body) Large Size Elevator B3 (after T-Rex event on body) Security Pass Room (adjacent to dead body on a shelf) Third Energy Control Room B2 Stabilizer Experiment Room Parts Storage (behind movable shelf) Transport Passageway (2 of them! behind shutter) Third Energy Area B3 Underground Heliport/Hovercraft/Hovercraft Storage