Originally Posted by TVthePunisher
Yeah, I forgot why it didn't x_x it's alright though, I did manage to get it unlocked eventually! I think it was with the other 3 players, judging by the unlock order I'm looking at here. That's right, you couldn't use the warthog/scorpion but you did get unlimited rockets (or close to it) on the back of the mongoose. Still, can't thank you enough for running through that with me!
It's no problem!
I'm glad I was able to help.
I think the achievement didn't unlock for you because you got disconnected from LIVE at some point. The same thing happened to me the first time I played ODST, and I had to replay a few levels.