The concept of the project was to replace that part of the factory wiring between the Tankwatch sensor assembly and indicator panel closest to the sensor assembly; this included corroded male and female disconnect connectors that had been placed in a difficult position for access. In addition, I wanted to provide for strain relief for the wires at the sensor assembly to allow for unscrewing the assembly for cleaning.
The existing wiring used 8-conductor Anchor brand signal cable (available at West Marine) with the red and black conductors unused as only 6 conductors are needed (the remaining conductors matched the colors used by the factory in my case). I cut the 
factory wire at a convenient point for placing a 6-position terminal strip terminal strip as shown in the first photo. (The terminal strip is by Blue Sea, available at West Marine, and has #6 screws; hence the 12 terminals should be for #6 screws.) I would add a note here that the factory used a plastic loom to protect this wiring and in that loom was other wiring; do not just cut the whole thing!!
I ran 6 feet of signal cable to the sensor from the terminal strip, routing it out of the way as best I could in the space forward of the engine belt guard. This cable was connected to the wires exiting the sensor with crimp-on butt connectors sealed with the usual goop as sold at West Marine and then the whole set of connections covered with a 3 ft length of shrink wrap tubing (1/2 inch diameter will shrink up about right). (I have not found this to be economical at West Marine; Moser Electronics or Mar-Val Electronics or any general electronics supply store will probably be cheaper.)
At the sensor, I screwed a small wire-tie base to the top of the sensor assembly and 
secured the bunch of 6 wires to it with a wire tie as shown in the second photo.
In use, I can unscrew the sensor assembly without disconnecting at the terminal strip for minor cleaning; and I can disconnect if needed for more serious cleaning.
Frank & Marian Johns
Reward – NT 32-227
sdjohnsfam@adelphia.net