I can't tell you when they changed (about 73 sounds right), Mopar put in shorter sun visors that were only supported at the door edges. I believe the mounting holes for the visors and the rear view mirrors remained unchanged, in which case you could just mount the older visors & mirror. I suppose in the worse case, you might have to drill new screw holes.
I don't believe you can swap the visors across the body lines though, your A body will need to have A body visors. The length of the visors, and the angle of the mounting pad changed between bodies and when they came out with the glued to the windshield mirrors, lots of stuff changed. Gene