Tom is also right about that I would give the same advice there. I do talk the same no matter which forum I am on.
If you will look at the slide-a-link it really does nothing except to keep the front of the leaf spring from bowing or winding up. In the 1960's on street performance cars we had what was called traction bars. They really did help traction some but not like we all thought. WE knew that they stopped the font spring from winding and releasing making wheel hop. That was what they were for. They did bind up the suspension some when the suspension was in movement so they gave a rougher ride.
Brilliant Ed Wilson, decided to try a diferent idea to keep the binding out. I still mounted the rear brackets to the same place. I still ran a bar from that to the front under the front leaf, just like all traction bars of the era did but my bar was a little heavier. Instead of the front mount welded solid to the frame like everyone else did, I made my front mount to pivot with axle movement not allowing any binding. Bear with me a little in your imagination. Attacjed to the lower part of that front pivot was a shock absorber pointing forward and up at an angle, the other end ogf the shock was mounted to the frame. It did work to keep the front spring stiff with no spring windup. The bottom bar was not binding anything because the front mount would pivot. The shock controlled the resistance to the bottom bar pushing forward.
In essence that which I did way back in the 1960;s is how the Slide-A-Link is supposed to work.
The Cal-Trac does still allow the non binding leaf spring up and down movement, The Cal-Trac converts the forward spring push energy into a lever force becuase of the rocker design. Any forward force of the front part of spring results in a downward force on the front part of spring to prevent spring wrap. By them moving the front eye attaching point further downward they have in essence lowered and shortened the point of Instant Center, which most leaf spring cars already need. You do have some slight adjustability in the design, which allows you to fine tune the amount of tire hit it will allow. Bottom Line is they work and were proven on Calvert's owwn car before he tried to market them.
Ed