I was inspired by this thread to do this mod on my kids' '65, when two sets of "one inch lowering" springs -- one set a 4-leaf "mid-eye" from Mustangs Plus, the other a 4-leaf 153# Eaton set from NPD -- gave it the 4x4 look.
I looked high and low for those U-bolt clamps like Opentracker has, and finally I gave up and made my own out of some bar stock:
Just a suggestion for those who have the same prob I did to find the U-bolt clamps. I heard after the fact that a spring shop will bend up the bolts for you, but if you've got the materials sitting around and you don't like to depend on a vendor for a one-off part -- in my experience a toss-up with a visit to the dentist -- you can make your own.