hi im wanting to wire up fuelgauge i have standard beetle tank and clock sender unit on tank has one pole for a wire please explain the back of clock has a little oblong box i left it alone ive wired up everything else an all work ok i just wasnt brave enough an didnt want my hard work going up in smoke  thanks guys

+ve ign feed goes to one side of the trembler/vibrator, other side trembler goes to the gauge, other side of the gauge goes to the tank sender. Both the tank and speedo case need to be earthed.