Shown below are a dozen NOS A-17759 bumper bar spacers. This is the barrel style which is constructed by two stamped steel shells spot welded on the ends to an inner steel tube.
These have a horizontal seam in the middle of the spacer between the two halves, and have a very good appearance and fit to the bumper bars and bolts. The outside diameter is larger than the typical rolled bushing style spacer, and the punched holes in the barrel halves fit the bolt better to center the spacer on the bar.
The more common style of bumper bar spacer is just a simple rolled steel bushing with a seam running the length of the spacer, and it does not fit the bar or the bolt as well as the style below.