this is it, its a faria 60-220 degree Fahrenheit in white on black (20-100 degrees Celsius below in blue) works fine. Was in my sharp so I know it works with 200hp blackmax just fine. All analogue Mercs run the same wiring setup. purple - positive (ignition), black - negative, tan - temp signal. I will wrap it up and get a quote from post office. Call it a couple of quid for the packaging?
I do have a matching tacho, speedo, and volt gauges if you want them but I would have to test they work and work out a price (it wont be a lot).