Help with MSD 6AL and billet distributor set up

I'm looking for some help with my MSD 6AL system. This is the old non-digital set up that I've been using for 20 years. In running diagnosis there are 3 wires TO the box: a red and a black big wire that goes to the Battery and a serious ground, and a small red wire that connects to the original positive lead to the coil that comes out of the wire harness back near the coil. The big wires show exactly the same voltage as the battery at all times. My small red wire, which turns on with the key in the "run" position shows 6 volts, both at the original wire from the harness (grey) and at the box. Is this right???? Is there something in the system that reduces this voltage for some reason?

Wires that run OUT of the box are an orange and a black wire that goes to the coil, and a pair of wires that go to the distributor (which is a newly rebuilt pro billet - work done by MSD). Is there any way for me to check that these wires are doing what they should?