In my experience manufacturers of all sorts of products use labels and other marks to track the identity of component parts - doing so is vital for stock control, quality assurance, change control and general manufacturing management. In many plastic injection moulded or metallic cast parts for example you'll see the part number moulded in. So your Stingray label is almost certainly one used for internal manufacturing process control. As to what it means, who knows. It was important at the time the instrument was built but probably of no significance afterwards.
Same with the neck and body having different date stamps. It's all about the manufacturing process. Almost certainly, necks and bodies are made on different lines, after which they'll be held in stock till needed. When an order is received to build a bass, a body and a neck will be brought out of stock and bolted together on the assembly line. So there'd be nothing odd at all about the body and neck having different date stamps.
P