Insulation in exterior walls
Insulating homes did not become common until almost a decade after your home was built.
Be that as it may, by blowing in insulation you can never be sure you have filled the stud cavity properly and you can never fill all cavities properly.
Also, blown insulation will compact over time and leave your stud cavities less than fully filled in short order.
It is best to gut the walls and install fiberglass batts in most instances.