For many applications, shaft weight is not a factor. For most bracket cars, consistency is the goal, so the performane advantage of lighter materials is usually not important. All MW mild steel shafts include Spicer weld yokes and lube for life 1350 series u-joints.
4" O.D. x .083" mild steel shaft, Spicer weld yokes, and lubed for life 1350 series u-joints.
4" x .065" steel shaft, Spicer weld yokes, & lubed for life 1350 series u-joints