I'm working on replacing my shackle and spring bushings with some greasables from ORD. Step one is to unbolt the leaf spring. How do I know when I have the tension off of it? I have the frame jacked way up on stands and a jack under the axle, so I can move it anywhere, I just can't tell when the tension is off. My Hanes book just says "remove tension", like it's obvious. Any pointers? Thanks!