need some torsion bar help…

hey all- trying to understand the way the torsion bar mounts in the crossmember ('73 Scamp). The rusty crossmember busted and the back end of the pass. side torsion bar isn't really torsioned anymore. Or attached, for that matter:(.
I've never worked on a torsion bar setup despite many years of Scamp/Duster ownership and I'm trying to understand this.
(the car is at my brother's place, so I can't take a look to see how it works)
I was looking on autorust tech and found this (I also noticed that BadArt posted a link to the exact same unit in another thread):

On another thread I saw pictures of torsion bars, and I see that the back end is hex-shaped (?)
I can't figure out how the A.R.T. part fixes the problem and re-mounts the t-bar (seeing as how it just has a round hole where the bar mounts)
Can somebody explain what I'm missing here?
TIA
Author: admin