tach signal from coil pack used for oem analog tach?

[85begalttype]

im currently building a 86 cutlass with a 85 hot air motor. Im using the turbo wiring harness under the dash. The cutlass has the rally pack gauge cluster with the tach. Can i use the green plug off the coil pack to feed the tach input (ive already switched the back of the tach for 6cyl) or will i need something else?

ive already matched the gauge cluster wires from the cutlass to the regal harness, all thats left is tach

 

[aminga]

The output from the Coil pack is a "square wave" Some tach like a VDO have to be modified to accept it.

 

[85begalttype]

is the green plug wire at the coil pack the same connection as the white wire in the dash harness? the one that goes to the rpm/boost meter?

 

[aminga]

I think so. It's been a while since I looked at the circuit diagram but I think they call come from the same coil output