That clip, 381619-S2, was documented as being used on all manual transmissions for years 67 thru 70, on the "Z" bar lower end. It's the only application. I know it exists, I have some on the shelf. Being the application in question was a Shelby, that may have had something to do with a different clip being found. As some have asked - what plant? A disclaimer on my part, most of the cars I see on the West Coast are San Jose built.
Jim