Armored Core 3: Silent Line

Beating all missions and getting a S-Rank in all of them will unlock various parts. Competeing 11 missions with a certain type of leg part will unlcok a new leg part.

Just like in Armored Core 3, there too, is an extra arena for you to dominate. To unlock it, simply beat Mobius, the A-1 rank raven. Once you've done it, the extra arena appears next to the regular arena. It's 2-on-2 battles with 2 opponent AC and you and a partner. You can even pick your AI AC as a partner!

Press Start and Select while looking at a defeated Arena AC. You'll hear a tone telling you that it worked.

The MWC-OC-30 back part is in the mission ''Investigate the Unexplored Region''. I suggest taking a heavy tank armed with a long range weapon to take out the pesky heavily armed bazooka launching MTs. But make sure you have a fast weapon, such as the LQ-15 or the CNG-300.

First take out all the fast moving MTs. Then when the heavy MTs are left. Go to the center of the map where the wreckage of the plane is. Blow up the back and go inside, the OC-30s will be inside on the left.

Then after you defeat the MTs, two unknown ACs will come after you. I suggest getting in the whole, the getting out of it and getting to the opposite side of the plane opening, VERY QUICKLY! If you're lucky the moron tank will get stuck in the plane leaving the other, lighter AC to you. After you're done with the AC, go after the other, it doesn't fire much, just unload all your ammo on him and he'll die quick.

After the missions over you should get a hefty sum of money and two MWC-OC-30s. If you're low on money sell them, they go for 99,000 a piece.