I spoke to John, He says that the shift cable is not a Volvo supplied part but installed by the boatbuilder. As Mike mentioned, these cables have been used for many years. There are three possible cables:
Morse=red cable jacket
Teleflex = Black cable jacket
Volvo = Grey cable jacket.
Teleflex purchased Morse so the red ones may go away.
Telflex makes a Supreme and a Extreme Cable. John heard that the Extreme was better but more expensive. I went to West Marine. They had a Supreme and an Extreme. They were both the same price. The counter person called Teleflex and asked them if the Extreme had a stainless cable rather than a galvanized steel strand cable. The Teleflex rep said that the Extreme was stainless. However, I checked with a magnet and the cable is not stainless. Bought it anyway and plan to change every two years.

I am going to mount and section my old cable to see what happened. It is curious that some cables last a considerably longer time. There is a ground strap right on the clamp that attaches the outer jacket to the outdrive. However, since the inner cable is plastic sheathed, it is difficult to say if there is good electrical contact. Also, the end of the cable is cut and at location there is no galvanizing. Seems like salt water can enter the end of the cable and start working it's way up. Once it gets a way up the swaged area, the strength is compromised.

I am going to run a pair of wires from the Accessory Stop button on the engine to an Emergency stop button located at both control consoles unless I can determine where the wire pair originates. I suspect that the wire pair comes from the main control computer located in the pilot house to the engine. Does anyone have a wiring diagram for a D4? The interior console can use a standard industrial ESTOP. I have one left over from a control job. I have to look into a liquid tight switch for the upper console.

I fixed all the damage areas on the hull and put on the first coat of epoxy barrier paint. Tomorrow a second coat followed by two coats of "hard" bottom paint and two coats of soft ablative paint. Hope to be back in the water by early next week.