rear end issues, tire rubbing on drivers side

So here is my issue, I have a 69 dart that I swapped out the /6 904 and 71/4 SBP for a 74 dart 318/ 904/ 7 1/4 BBP . I did the swap about two years ago and have had a little tire rub on the passengers side rear tire only if I hit a sharp right hand corner to fast. Very minimal issue.
Last night driving though San fran at 10:30pm the drivers tire started to rub the side of the tire on the drivers rear. The out side of the tire rubbing against the inside of the fenderwell. I stopped and checked it out and you could just get your fingers between the tow and the drivers rear seemed a little lower on that side. I decided not to have it towed and drove on only to have more rubbing about a mile down the road, but it seemed to happen like something shifted and then rubbed so I steered the car back and forth to make the rear sway back and forth and it seemed to do the trick because I made the rest of the drive home on the hwy 50 miles without an issue of more rubbing?
I'm looking for suggestions as I got home late 11:30 last night and had to work all day today.
I was thinking the rear end axle shifted, or a blown shock or the rear sway bar stock from the 74 shifted.
Thanks in advance for your suggestions. Ted :prayer: