The 65-66 rear axle perches centering locator holes are raised 3/8” above the top of the spring. The original springs had longer locating pins to work with that condition. Replacement springs have a 1/2” diameter dowel that is 3/8” long, or less, so the dowels do not index correctly in the spring perch, leaving about +/-  1/2” play front to back.
To fix this, I ground some big flanged nuts to a little less than 3/8” thick, then drilled the nuts to 1/2” I.d., then welded them into the axle’s perches.  The rear end then indexed perfectly on the spring’s dowel pins.





dc greens