In places with military outposts, Crane might find a green military crate. These crates hold valuable "Experimental Military Part" blueprints that Crane can use to upgrade his dirt buggy. The parts that you can make from these blueprints are of the highest quality and even higher level than the level 5 parts that Crane can upgrade to from his driving rank on the skills menu. In order to open these crates, Crane must have received the military keycard from Jasir that closes out The Gathering story mission.
During the Crash Boom Bang side quest, Crane will get a tracking device from Tolga and Fatin that is supposed to be used to find their boss. This device can also be used as a tracking device for finding military crates. It will beep faster as Crane reaches the crate, sort of like a "hot and cold" game.