Why can I not discover or change to this truck ?

Smithville Dam. Marshall truck not discoverable or drivable, but available on the map to be discovered.link text

Same Problem on xbox one x. Has to do with some sort of bugged quest. Your are supposed to repair it and retrieve. The quest completes after repairing, but does not allow you to retrieve it. I towed to both smithville and black river garage and no go on discovering it.