Mopar Muscle Association UK

Question
My 340 Chally has been fitted with a MSD Pro Billit dizzy at some point, and now the tach dos'nt work, according to the MSD web page the grey wire is the tach hook up, but its just lose and not connected?
i tried a fly lead from this direct to the grey/red on the back of the tach still no joy, i read somewhere that a smart box is needed to connect the two but MSD dont make mention of this?
Obviously the tach could be toast but looking through the paperwork ive got , the tach stopped working when the MSD unit was fitted???

any one got any ideas?

Thanks...............................

I know that they make 2 different tach adapters, I have one of them, I will have a read up....

My grey wire also not used - pretty sure i ran my tach off the coil post.