You want 1 of 2 things... the track locator
or the wishbone... I have both on different
cars... the street rod I use the track locator
(thats the rod that angles between the ladder) bars)
and when you mount it use the lower rear hole on the
diff and what ever hole you have the front bolt in is
where you mount the front locator.. that way it pivots
in the same arc as the ladder bars... a wish bone is
more for the track.. I mount the single point on the
diff and I use the fronts in same holes as the bars..
it has a sliding inner tube which you need to keep lubed
so it slides.. another thing you might want later is a
anti roll bar.. that depends on if things are flexing...
a track locator is the easiest.... the angled
bar is the locator
EDIT
It is HIGHLY advised to add the back brace if
your using a 8 3/4 or a 9"
Also.. get the double adjustable ladder bars..
makes life much easier