trim & oil gauge wiring problem

i have a 6y5-83670-11 3 wire trim gauge to convert from my digital gauges on a 1999 150 sw series outboard. the wires from the boat are pink, orange, black and grey but on the gauge there is pink, orange, black and yellow, i assumed yellow was switched power but then what is the grey from the boat? also the black from the gauge harness splits off into a sgl black which i assumed is ground.

also, on the tach 6y5-83540-05 the oil lights are red/black green/red yellow/red black/red and the red is not stripes but rather a tick mark every 2" or so, on the boat i have green and green/red, which from the boat diagram one may be overheat and the other oil warning? what goes to what?

thanks for any help you can give, the instructions with the gauges are useless

[boats.net]

You will need 68F-82553-70-00 wire harness connects to motor and to gauges for oil level and trim sender.