John M., yes, the narrow frame blade lift rods should all be the same length. However, there's no guarantee that a PO didn't mix up a narrow frame lift rod with a wide frame lift rod with either a narrow frame or wide frame snow thrower lift rod.
Should you find yourself with a blade and a lift rod where the lift rod just doesn't seem correct, do what Steve Blunier demonstrated here, park your Cub with blade onto 2x lumber with the blade resting on the ground/floor, to figure the proper length. It's quite easy to fab up a lift rod.