I've got 71 Duster 340 rear springs in my 65 Barracuda; put the 65 Barracuda's springs (HD) in my 67 Barracuda back when it was still a slant six (now 360). Only reason I swapped Duster 340 springs into my 65 Barracuda is that they only had a little over 100,000 miles on them, instead of well of 200K on my original 65 springs.Question, The Hotchkiss Leaf springs says 1967. Will they fit my 1964 ? or did the leaf spring design change in 67?
So yeah, 67 rear springs will fit your 64. Also 63-72 torsion bars.