If there are other vibration sources such as a worn main shaft rear bearing or a bad U-joint then replacing the worn rear engine/trans mount will not completely fix the situation. The drive shaft can also have vibration issues. Clutch & flywheel issues are also a possibility. I'm with Kube on this one. The mount was adequate for a car with no issues. Ford thought the final mount system through 1948 was so good that they didn't need steady rods but when they fail, there is a bigger problem than just a failed mount. They probably should have kept the steady rods. Change it if you want but the improvement is not that much of an improvement.
