I want to be sure! 71 challenger rt

[MerlinsMopars]

Approaching the end of the rebuilding aspect and looking for some help with the msd 6al2 upgrade. The issue is with the tach and 8920 adapter upgrade.
Firewall slot # 20 has a grey wire on the inside and white wire outside of the firewall. I am assuming it is the tach trigger which went to the - side of the coil originally. Is this a fact?
According to the msd diagram, I need to know if it is a current triggered, or voltage triggered tach.
So many different posts for different years and alike cars which is making it hard to dicifer what is correct.
Been thru many posts but I want to be sure.
Final countdown till break-in.
Disinformation is as bad so I need help.
Is this correct, and the tach wire from the firewall correct?

Thx for any help.

 

[72RoadRunnerGTX]

Voltage triggered, yes, cavity 20 in the bulkhead connector was used for the tach signal run in '71.

 

[MerlinsMopars]

Thanks. Very much appreciated. Violet wire from the msd adapter to the original tach trigger wire.
Is it ok to connect to the blue/ white - brown wires that triggers the start/ run for the msd control as the red wire shows for the adapter in the diagram?
Strange that the start and run circuit stays live all the time for msd but I assume that is ok inside the circuit.

 

[72RoadRunnerGTX]

Yep, connect blue/white (IGN1) and brown (IGN2) together for the ignition on sense lead for the MSD and tach adaptor.

 

[MerlinsMopars]

Yep, connect blue/white (IGN1) and brown (IGN2) together for the ignition on sense lead for the MSD and tach adaptor.

Thanks again for the quick and direct info. It had been a while since I took everything apart. Most was labeled except the coil and now my wiring is officially complete. I went with msd controller, distributor and coil to limit the rpms and that system works well. A few more parts to install and this car will come back to life. I went thru so many threads trying to figure it out and just couldn't find as direct of an answer.

 

[Ricks72Chlgr440]

Nice car, well done!