Just as Ford assembly line techniques used daubs to indicate handed and "correct for application" parts.....
DYES on special bolts/nuts continued to signal TORQUE TO SPEC or NEED IN PLACE TO RUN.
As information flowed, on reviesed plant proceedures or after delivery dealer TSB's fixing area issues refered back to confiming placement and torque specs to insure car's didn't have "common problems" in certain areas.
Grounds for the new ECC-IV system were especially important as ANY LOOSE or missing hardware of the terminated circut could create non-run or worse field failure where the problem was "chased" at the dealer level.
Mark