ok well first things first, did it come with the after market senders to replace the stock holden ones? and guessing that u have an SL/E its a V8?
The senders are important cause they screw into the block and manifold where the holden gauges senders were to get a correct reading. I tried to use the holden ones for these gauges and they gave me some wild reading (lol 200celcius at idle? i dont think so).
Alright, now i have lost my little diagrams but i will try n remember. Now are there ANY marks next to the wire contacts to say wat ones are wat? If i remember right, the middle might be the signal wire but its all in the air im affraid. Remove all of those loose wires and it should say something.
Do u need to also know where on the block the wires go as well or do u have that sorted?
Those red wires go to a power source...ignition source is the best way to go (so the gauges come on with ur igniton). The black is earths, and the greens would be to go to the senders......well thats how it would normally be if ya go by colours....but with the way the lights are hooked up, maybe the greens are earth, and the black is to the senders.....there will be something to describe them there. If ya can't work it out, let me know coz we recently pulled a set of those out of our race car so I'll go have a looksy.
As for the senders....maybe look in a Speco catalouge, which Repco would have. They are electrical gauges so make sure u get electrical senders. Mechanical oil psi gauges have an oil line running to the back of the gauge, and the mechanical water temp has a copper line going to the back of the gauges. Electrical ones are legal (which is wat u have there) but mechanical ones are illegal, the reason being if the oil line bursts ur gonna get a face full of oil.
The negative, just join them both together and chuck a ring terminal on the end and screw it into something metal on the car (or use an existing screw).
The power wire ya could run from anything which has power (use a test light). Look for a wire which is live with the ignition on, and off when the ignition is off, that's the best way.....well the best way would be to run a new wire from the fuse box, but ya don't have to do that.
The wires for the lights will be a power and earth. Ya can earth these out on the same earthing point as the gauges....but for power it's best to find a wire which is live when the lights are turned on (and goes dead when ur lights turn off), and tap into that.