Take a good file and make a stroke across the area where you want to cut the shank. If the file teeth bite in easily then it's soft enough to cut with a saw. If the teeth don't bite in, then it's probably heat treated.
Take a stroke across the shank of a drill bit to get a feel for hardened metal.
2006 23B Hybrid with 10k round bar WDH
2011 F150 4x4 SCREW Ecoboost, Max Tow, Integrated TBC, 3.73 LS axle, Firestone Ride Rite airbags.