I was looking at Google Earth at that area, and I see Weapons Test Ship 892 in a wharf nearby. On GE, the wharf where 075 went has three LNG carriers, one of which is red, possibly the same ship or ship of the class as the Knutsen OAS tanker we saw in the photo of Type 075 at the Shanghai Huarun Dadong shipyard. This part of the island might be HDZ's and not Jiangnan's. Sometimes the shipyards are set close, as Shanghai Shipyard's and Shanghai Huarun Dadong Dockyard's are set in Chongming---- both of these shipyards are traditionally in the Shanghai proper but closed their old shipyards, sold the land to real estate developers, and moved to Chongming. I think Jiangnan's shipyard is set next to HDZ's and another CSSC shipyard and they are sharing facilities, as all three are under the CSSC, now CSG banner. The three shipyards make up one super shipyard.
The proximity of the shipyards makes me think the 003 carrier might even be a joint project between HDZ and Jiangnan.