Actually that is the standard stainless hub insert and the stock derin bushing for the 1" shaft.
The part number you need is 849501Q1. We have them in stock. They list at $28.98, we sell them at $24.35. There is no c-clip holding them in place. They simply slide in with a interference fit. There is a trick though, they are tapered and only go in one way.
The HD insert does have a c-clip but the delrin bushing is unavailable separately.
Brett