Note this regards a 1973 Pinto seat belt/shoulder harness.  Your arrangement may vary.  As with all alterations, "Do at your own risk."

The connection of the shoulder harness to the seat belt has been a continuous frustration. It seemed more often than not the harness would disconnect from the belt as I would attempt to connect it.  I tried staking the open end of the connection but this did little to help.

Today I was digging around my bins and found what I'll call "shaft clips" (see picture).  I was able to slide the clip over the protrusion and keep the two pieces from disengaging.  If you notice in the picture one end of the clip is ground down to facilitate letting it slide on.  I'd recommend checking and filing as necessary the sharp ends of the clip - especially the one that needs to be shortened.

Anyway, not sure if this has been done before but given the way it frustrated me, I thought others might be interested.  And, if you ever want to undo it, simply slide the clip off.

I can live with the sloppiness of the setup, but what I hate most is burning my fingers on the  blamed buckle in the summertime!
Dwayne

I'm surprised that more people aren't complaining about this problem. Virtually ever time I'd grab the seat belt, the shoulder harness (which is on top - and therefore predominantly what I'm grabbing) would slide out of the belt connection. The belt would then retract (1).

 I'd then have to gently pull out the belt (because it wants to grab unless moved at just the right speed) and connect it to the shoulder harness.  At this point the belt would slightly retract (2) when I stopped to make the connection. At the stop it would grab, coming short of being able to connect to the belt latch.  I had have to coax the two belts to retract AGAIN (3) - making sure they stayed together - and then ever so gently (but continuously) pull the belt/harness until I could FINALLY have everything connected.

As an experienced Pinto driver it sometimes took up to three tries to get it right.  My passengers often numerous attempts more.  No one else has had this problem? ? ?  Or do you just not wear your seat belt/shoulder harnesses?

Anyway, one last tip.  Even though I have now gotten the shoulder harness to stay attached to the seat belt there is the issue of the harness belt rotating and becoming twisted.  I used a wire tie through the cloth loops to keep that from happening.

These older type are inertia triggered to lock.  The modern stuff uses some type of electric/electronic sensor.  So, that would have to get figured out to make them functional.

 I was looking for the inertia type for my '64 Studebaker Daytona.  There are not many cars in the junk yards that still have them.  I found a set in a MG Midget, but the retractor had to be positioned "just right" or it would lock full time.  I finally found a non-retracting belt/harness in a Toyota Hilux truck.  I think there were only a few years that harnesses were offered without retractors.

The other thing is the Pinto has two separate belts.  Modern belts are usually one and the same. I don't know if that matters other than it seems more functional.