[argonaut]

gmjim,

The rear leafs are stock GM springs off of the 73 K20 donor: 6 leafs + 1 overload, 52" long, 2-1/2" wide.
The front leafs had already been swapped onto my 66 when we picked it up. They are Rancho 41054S: 5 leafs, 44" long, 2-1/2" wide. I think this is an obsolete spring because I've had a tough time finding any info on it. A quick google search gave me some info that these may be a 4" lift spring for a 72 pickup, with a spring rate of 720 lb/in.

The fronts hangers will retain that stock locations, being that stock springs were 44" long too.

I'm not really sure what the end result lift will be when I'm done. For starters, I have no reference for a 66 with stock springs. But also I've now got this mix of leaf springs and hangers. What I can tell you is I laid out the rear spring hanger locations to maintain geometry similar to stock, they just hang the spring lower. I know the front will sit about the same as in the photos on page 3 of this thread. Maybe slightly lower once the all steel big block goes in, but with this super stiff front springs it won't be much. The rear is a wait and see game. If it doesn't sit level I'll have to look into getting some 2" or 4" lift springs for the rear. Unfortunately I won't have these answers for a couple months until I get the powertrain and body back on it.

Keep the questions coming. Hopefully at least one other person can benefit from the tings I've had to figure out for my build.