Military ships and vehicles are hard to come by so Rebels have to make do with what they can get. An old resource controller, basically a heavy pallet tug for moving bulk cargo about in a shipyard, with it's many claspers and clamps for cargo had been refitted into an escort carrier. Now it's clamps hold several fighters and able to provide a nasty surprise for any Imperial patrol that stupidly thinks it's convoy of freighters is defenseless...