I have only yesterday replaced the fuel sensor on my 1990 420 DA. In my case, it was the Port sensor which was accessible via a small sliding door cupboard just before the cabin steps (on the left). Obviously Sea Ray don't make them anymore or whoever originally made them (possibly teleflex). I bought a 33-240 ohm expanding fuel sensor which are readily available and modified it. Basically, the one on mine was very long and the expanding one wasn't long enough. I had to replace the main shaft with small box tubing and replace the wire because that wasn't long enough either. I have attached a picture of the two.. The one on the left is the modified new one, on the right is the original.