Post a photo of the whole truck, side view. Then we can tell for sure if its lowered

There were actually a couple of (maybe 3) 3/4 ton "packages"
I believe the light one and maybe the middle weight package were the same as what they list for a 1/2 ton. That 7170 sounds familiar.

I wouldn't use the Cummins spec spring on a /6 truck. There was a light and heavy duty suspension, one way to tell was whether the tie rods were equal length or not
I believe the control arms are different between them too. It's been a while.