I know what the shackle is for but that described movement is exactly what I am trying to reduce. My set-up is similar if not identical to a lot of other 'homemade' traction bars out there so I like my chances. In fact, I found a lot more truck guys using my kind of traction bars versus the Caltracs. This guy '6600duramax' is on our forum board making and selling a traction bar which mounts the same way as mine.
http://67-72chevytrucks.com/vboard/s...d.php?t=364788
But, if the ride happens to be a little stiffer than desired, I can always add a small shackle to my front mount to allow my springs to elongate 'a little' when compressed. Maybe that will give me the best of both worlds. Either way, I appreciate the dialogue on the subject.