Arriving Shanghai via cruise departing by air back US

We are arriving in Shanghai via cruise ship. this will be the cruise termination point and we will depart Shanghai via air back to the US. We wish to stay another 2 days to visit friends in Shanghai. Can we obtain the 72 hour visa at the ship debarking area in Shanghai? Are the cruise lines capable of issuing us the transit permit documents prior to debarkation?

Thanks -- Brent