Talking 108 chassis..P/F did not come out on US version until '72 b/c of regulations.

Your 6.3 had it b/c your guy hooked it up...as my post stated ..it was in the car..but DOT did not allow it until '72. So the single wire for that Factory Circuit was in the harness at production, but taped back, unconnected , right there at the factory , to satisfy the then current DOT Export regulations w/o having to have different harnesses,,they just did not hook it up until DOT changed the rules.......
Any car after that had it hooked up.. Like your other US chassis.

The determining factor was US REGULATIONS. The FEATURE was ALWAYS in the car.
But NOT ALLOWED at that time in US only ........................
Same deal with the 113 cars ..if you have a Euro version, it is hooked up, if you have US version, it isn't ..[ but many are b/c US version guys know this trick, just like your guy did]

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A Dalton