You might need a longer shackle, and you might need to stand the shackle up at ride height a little more by moving the bracket back. You need to have enough room for the spring to go flat between the mounts and still have a little angle on the shackle, ie, it (the shackle) should not be totally layed out flat. I would bet the 6" spring is a little longer than the stock or 2" springs. That's probably the root of the problem. Be aware, you can put the brackets on the opposite sides of the frame and move the pivot point back 2" without drilling new holes. this is due to the offset amount in the bracket.
Making the world better, one truck at a time.
SW-ORD
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