Road Runner Nest

Iswapped a ralley dash from a 74 charger into my 72 satelite but there were no wires on the tach. where do they hook up and which one goes where?

There is a grey wire that attaches to the (-) side of the coil. On tach cars there is a post on the bulkhead for this. I'll need to check the manual for where it connects at the tach.