When you complete the following tasks the corresponding part will become unlocked. Some parts will only appear when you have a high enough company loyalty rating. If this is the case complete Story mode and return for the part when the mission can be replayed.
Unlock CAL-44-EAS (Arms): Added to shop as you progress Story mode.
Unlock CAW-DC-03 (Weapon Arms): Defeat rank A-1 in arena.
Unlock CAW-DS604 (PSP exclusive Back Unit): Added to shop as you progress Story mode.
Unlock CBT-FLEET (Booster): Found in mission 'Destroy Massive MT'. It's behind a hill in the northwest corner.
Unlock CEBT-HEX (Extension): Complete 'Safeguard Alloy Sample' without losing the transport.
Unlock CEEC-01-XSP2 (Extension): Complete 'Eradicate Life Forms' without breaking the gas canisters.
Unlock CHD-04-YIV (Head): In 'Defend Naire Bridge', it's below the start, on a platform under the bridge. You have to go to the open end and fly back underneath.
Unlock CHD-GLITCH (PSP exclusive Head): Defeat rank E-33 in arena.
Unlock CLL-EM-070 (PSP exclusive Legs): Defeat rank C-10 in arena.
Unlock CLR-00-MAK (Legs): Defeat rank A-3 in arena.
Unlock CWC-SLU-64 (Back Unit): Defeat rank B-7 in arena.
Unlock CWGG-GR-12 (Right Arm Weapon): Defeat rank C-15 in arena.
Unlock CWGG-HG-10 (PSP exclusive Right Arm Weapon): In 'Defend Helicopter Crew,' the part is on top of a pipeline to the northeast.
Unlock CWM-S60-10 (Back Unit): Awarded after first arena victory.
Unlock CWX-LIX-10 (Back Unit): Added to shop as you progress Story mode.
Unlock CWX-LIX-10 (Legs): Added to shop as you progress Story mode.
Unlock KES-ES/MIRROR (Left Arm Shield): Perform well enough in 'Defend Water Processors' to activate the bonus mission. Take and complete the bonus mission for the part.
Unlock KWB-MARS (Right Arm Weapon): Found on a beam under the starting platform in 'Destroy Massive Weapon.'
Unlock KWG-HZL30 (Left Arm Weapon): In 'Destroy Naire Bridge,' destroy both monorails that go by and complete the mission.
Unlock KWM-AD-50 (Back Unit): Don't get hit by a single missile in 'MT Training Exercise'.
Unlock KWX-OC-22 (Back Unit): Destroy ALL enemies in 'Destroy Germ Canisters' and complete the mission.
Unlock MAL-303S (PSP exclusive Arms): Defeat rank D-5 in arena.
Unlock MCM-MX/002 (Core): Added to shop as you progress Story mode.
Unlock MEBT-OX/MB (Extension): In 'Rescue the Survey Team', it's hidden in a nook in the wall to the left of the closed door.
Unlock MEST-MX/CROW (Extension): In 'Disable Pulse Generators', there is a breakable grate above one of the generators on the lower level. Go through this grate to find the part.
Unlock MGP-VE905 (Generator): Defeat rank D-15 in arena.
Unlock MHD-RE/H10 (PSP exclusive Head): In 'Destroy Escaping MT,' it's just outside the door where the real mission target appears.
Unlock MLB-MOONLIGHT (Left Arm Weapon): Complete 'Destroy Massive MT' without a consort.
Unlock MLB-T/100 (PSP exclusive Left Arm Weapon): In 'Assault Crest Facility', it's on top of the last generator.
Unlock MLH-MX/VOLAR (Legs): Get a good score in AC Test 1 (around 35-40 targets without missing).
Unlock MLR-MM/PETAL (Legs): Added to shop as you progress Story mode.
Unlock MLR-ZMX (PSP exclusive Legs): Defeat rank B-2 in arena.
Unlock MRL-SS/SPHERE (Back Unit): Found in 'Protect Crest Convoy,' behind a radar dish to the left of the revine near the start.
Unlock MWC-XP02/75 (PSP exclusive Back Unit): In 'Defend Energy Reactor,' it's on the floor in one of the right-side hiding spots on the way to the reactor.
Unlock MWG-HG/111 (PSP exclusive Right Arm Weapon): It's a the bottom of the molten pit in 'Bomb Disarmament'.
Unlock MWG-KARASAWA (Right Arm Weapon): Destroy the cannons as quickly as possible in 'Destroy Gun Emplacements' to activate a bonus mission. Complete the bonus mission to get the part.
Unlock MWG-SBZ/24 (Right Arm Weapon): Found at the bottom level of the ship in 'Recover Ship Cargo'.
Unlock MWG-XCB/75 (Right Arm Weapon): Destroy the enemy AC in 'Defend Ruglen Laboratory' and complete the level.
Unlock MWGG-XCG/20 (Right Arm Weapon): Added to shop as you progress Story mode.
Unlock MWI-DD/20 (Inside Part): Found in 'Defend Water Processors', on the ground behind the pipes to the right of the mission start.
Unlock MWR-M/45 (Back Unit): It's behind an outcropping at the top of the dam in 'Safeguard Water Supply'.
Unlock MWX-MX/STRING (Back Unit): Complete the game.
Unlock OP-E-LAI (Optional Part): Defeat rank C-5 in arena.
Unlock OP-E-LAP (Optional Part): Added to shop as you progress Story mode.
Unlock OP-INTENSIFY (Optional Part): Complete the game.
Unlock RIX-CR5000 (PSP exclusive Radiator): In 'Eliminate Infiltrators', after opening the door to floor 6F, it's along the far wall.
Unlock RMR-ICICLE (Radiator): In 'Defend Personnel Convoy', don't lose a single ally vehicle.
Unlock VREX-WS-1 (FCS): Defeat rank D-10 in arena.