74 Duster rotted out drivers side torsion bar crossmember

Is the crossmember so bad as to make welding not an option? Sometimes cracks develop rather than deep rust. If the cross member is in a surface-rust-only state, then have the t-bar sockets re-welded into the x-member. It might take some plating added for a good weld.

Otherwise, you should be able to buy a use from a parted out car.