Many people run the Chevys without any sort of traction bar, they springs are quite thick and resist wrapping, but they are so long that they still flex well. I would install them first and then see if you still need a traction bar.

As for the bar itself, I really like Budbuilt's bolt-on design with a shackle. It would provide more flex than using the torque arm (because the shackle works in conjunction with the springs) but still resist axle wrap (because it mounts in two vertically seperated points on the axle).

Harry Wagner
Harry Situations
4x4Wire's Toyota Section