Jim,
The RH torsion bar broke on my 66 Sport Fury while I was driving to work
one day in 1982 or 83.
I was zipping along an undulating 2 lane rural road at about 45 mph when
I crested a little rise in the road. As the suspension compressed on
the other side of the rise, an awful CRRAAACCCKKK! sounded and the right
side of the car dropped markedly. I drifted to a stop and took a look
under the car. The bar had broken about 6-8" from the control arm end
and it was an engineering textbook perfect torsional failure -- the end
of each broken piece looked like a spiral staircase.
I drove the car home (feeling every ripple in the pavement), installed a
spare bar, and made it to work by noon.
Pete in PA