back in the 80s I had a 76 Charger and a 75 Cordoba. Dad had a 78 Monaco wagon. seems like all of the "late-B" bodies were all like this. My current 78 Sport Fury is the same way. Nature of the beast. I remember seeing a tsb somewhere about this, where they said to put smaller wheel cylinders on them for the issue.
All the others I mention had had their rear brake shoes replaced during our ownership. My 78 still has its original everything on the back. (only 54k miles)

I also remember in my work, seeing a tsb (yeah I know, not a Mopar) about Rangers, Aeroflop vans from the late 80s/early 90s and I don't remember the complaint (besides being Fords) but the tsb said to replace the shoes and they gave a pn for the updated shoes..... IDK what you have on tehre for brake shoes, but unless you have some OLD stock on there, its hard telling what the composition of the brake linings you have may be.....