Try Buck Algonquin. They may have one, or be able to direct you to a source, if it’s still made. Photos and dimensions of what you are trying to replace would be helpful.
I was not so lucky when I needed to replace the bronze shaft log tube on my ‘82 H30. The part was out of production and I had to have one machined. Fortunately, a local machine shop that works with my yacht yard saved the day. I just gave them the old one as a template. I think it cost around $120 US, but that was about 12 years ago.