I had an old Bronco once that always pulled to one side. I did everything I could think of and finally sold it. The guy who bought it took it to a garage and they found the opposite rear wheel seal had gone out and got 90 weight on those shoes. Because that side wasn't working on the rear, it made me think something was wrong on the opposite front.

'65 C-10, 65 L-60, 65 C-80, 72 C-60 & and a bunch of old Chevy cars.
Never time to do it right, always time to do it over.