Charles:
I have vague memories of getting one at a local store in Alameda... maybe the outboard motor shop or Svendsens - but I have no idea if they do mail order...
https://www.outboardmotorshop.com/
https://www.svendsens.com/
Maybe take the original to a full service auto parts store? 32 years ago I used Davis Auto Parts in Watsonville when I taught auto shop in the area ... no idea if they are still in business.
Hope this Helps
Jay