For any Rangers looking to use the Toyota long travel leafs with a SAS, I have a slight alternative for the front: http://www.trail-gear.com/leafsprings.html
Their 5" HD springs would seem to be better suited for our larger (4.0) v6's.
I make this observation bcuz the rear All-Pro leafs, even though, or better chance bcuz
they come with more leafs than the corresponding fronts, seem to have more articulation (mostly upwards). I feel that the weight of the front is more than that of the typical Toyota which they are made for. So more weight means the leaf saggs more, therefore it has less travel upwards.
I'm stickin' with my current front leafs, but may try them out in the future if I don't ditch the leafs first for another setup. If anyone goes with 'em, be sure and let us know how they work!