Unless you have a V-8(which you'd already have the traction bars), you DO need brackets on the axle for the factory traction bars to bolt to. The V-8's are the only Explorers that came with the traction bars. The brackets on the axle that the traction bar bolts to is welded on at the factory. Since the V-6 models Explorers do not come with traction bars, they do not have these brackets.
Traction Bars: F67Z-4A479-AA (2ea)
The frame brackets come in 2 pieces per side. They are as follows.
Inner piece: F67Z-5D493-AA (2ea)
Left & Right side outer pieces: F67Z-4A218-AA (1ea)
F67Z-4A218-BA (1ea)
I can't find my receipt for the springs, however the tag on the springs show the following part number: 1L2Z-5560-AA
Package of 4 bolts for the traction bars has a part number of: W701865-S426.
Hope this all helps...