I searched Google for "shoulder belts dodge dart" and found a few pages. One guy had a '66 he added shoulder belts to but doesn't go into detail. Maybe you can email him. It's the first link on the search.
If you want we could trade my 97 Neon ACR for the Dart, it's got shoudler belts...
A friend in high school had a 64 Fart, swapped out the D for an F from a Ford. We used to hide three in the trunk to get in the drive-ins and it was an excellent car to hit the big plastic garbage cans with...
_________________________
Dave Clark
Georgetown, Texas
MK2A 42Gb - AnoFace - Smoke Lens - Dead Tuner - Sirius Radio on AUX