As noted by chevycop, '27 and '28 headlamp buctets appear to be identical, but they are not. '27 are slightly smaller at the rim attachment area and when attempting to install a '28 rim on a '27 bucket they will either remain loose or separate from the bucket. The diameter of the headlamp buckets, at the rim attachment location, is 8.25 inches on the '27 bucket and 8.562 inches on the '28 bucket. The physical size of the two buckets appear to be identical but the rim attachment portions are slightly different in size and shape.