Cheers guys for the quick responses - I am using one of these units
Supplied by saturn complete with a sensor to go straight into the gearbox. The warning lights around the side are little hexagonal units you can swap or make your own to suit - you get these in the pack
The only thinh you have to be careful about is that 4 LEDs on one side are +ve switched and the 4 on the other are -ve switched.