When I purchased my backhoe, it came with another bucket that makes ripping tree stumps much easier. The only downside is the diameter of the hole for this bucket is about 1/2" larger than the bucket it came with where it was nice and snug. Are there steel spacers for this sort of thing so the pin isn't moving around? Is there a chance it will bend over time? It's about a 1.5" Diameter hardened steel pin.
Find a machine shop locally and have a set of bushings made. If it is a different width you can also take care of that with collars on the bushings.
A second to getting some bushings made. Used the way it is will cause excessive and uneven loading of the pin. Pin will have reduced strength since loading will now only be at a pinpoint of the diameter instead of being displaced across the entire cross sectional area.