I'm pretty sure they're durable.
Disposable often just means that components are welded, not bolted together. Major components are designed to be unit changeable-- i.e. old engine blows up, change out with new engine, throw old engine away. This cuts down on having a warehouse full of spare parts. A good-sized conex box would hold a couple of spare engines, spare transmissions/transfer cases, maybe an axle or two, a complete wired spare body and you'd be good to go.
If I'm not mistaken, one of the provisions of the contract was that ALL tooling, assy. jigs. spare/extra parts were to be turned over to the Marine Corps when the last of the vehicles were delivered. Makes maintaining a mighty mite a real challenge.