Here's the second mystery electrical box under the hood of my '73 Duster

I figured out what the mystery aluminum box was. It was part of the add on cruise control system. My handyman and I worked on the car yesterday for a few hours, and had a good game of "What does this wire do?" going for a few hours. He is half my size, so he got the job of crawling under the dashboard and up under the car. This box had wires coming from it, going to the cruise control switch that had been installed on the end of the turn signal rod. It has a hose going to manifold vaccum, into a vaccum switch looking component in the box. The part with a round white end, and gold colored tape on it. It had a pair of wires running down past the transmission, to a sensor and weight zip tied onto the driveshaft for a speed indicator. And other twisted pairs of wires going to the main cruise control box.

The soldering job on the circuit boards in this box was so bad, and the whole system looked so hacked together, that I doubt if the cruise control system ever worked properly, and if it did, I certainly wouldn't trust it. Mystery solved.