I don't think there is sich a thing as a "torsional strain gauge". Strain gauges measure direct strain. If you have torsion in a circular shaft for example, there is a shear strain on the surface of the shaft which is equivalent to equal and opposite direct strains at 45 degrees to the axis of the shaft. So you just use two "ordinary" strain gauges at 45 degrees to the axis.
A strain gauge rosette with 3 gauges 120 degrees apart will measure any two-diimensional strain field.