tyring to install a sunpro super tach 2 in my 96' 4.9L i have power, a good ground and illumination, all im missing is my rpms. which is supplied by the green wire but im having a hard time connecting it properly ive used this diagram for reference
http://www.tradervar.com/All%20Other%20Sun%20Tachs.pdf
but im still stuck...thanks for any advice in advance

 

Find the negative wire on the coil, the green wire goes there.