That box hanging on the bottom rail is a transformer for a big color head.
Ah, and the steel tape is a attached to a counter-weight spring in the box.
Even for Beseler that's one heck of a kluge. I second the advice: get rid of the box.
As to the stabilizer: if it hums like the dickens then it is possible to plug the stabilizer between the timer and the lamp, that way it only makes noise when you are exposing. The stabilizer was meant to go with the color head and kluge box: it isn't really needed for black and white printing and you may be better off not using it.
There is a switch shown on top of the stabilizer: where does that switch wire lead? If it goes to a AC flat blade plug then it is meant to plug into the
bottom outlet on the motor box. It was meant to control the lamp in the days before timers. With a timer you would just leave the switch in the on position. Don't try plugging it into the power line.
I like to be able to move the head without having to turn on the timer. I have an extension cord from the timer that is tied to the top of the chassis and that the head plugs into. I have the motor directly connected to the AC power. If you do that then you don't need to worry about a shorting plug or switch on the motor box. If you want to keep the voltage controller then unplug the voltage controller from the motor box and plug it directly into an extension cord from the timer, leave the head plugged into the voltage controller. The voltage controller is an anachronism and can be dispensed with if desired.