Brand new distributor, with several different advance curves.
Your original ignition coil can be used with this new 123 distributor, as long as it is in good shape.

Coil has only one connector, this is for the black wire.
The red wire has to be powered by 12 Volt when the ignition switch is on.
The aluminium housing makes ground connection via the engine.
Keep in mind that this new item will give a stronger spark, which might cause worn cables and coils to fail.
Will work for piont distributors, will not work with pulse distributors.
This unit easily connects to your computer via USB for additional live tuning.

How to connect your 123 distributor