New '40 speedo cable different threads?

[Coupe de Gras]

I recently purchased a 1940s speedometer cable to attach to my 1940 deluxe Speedometer. The threads on the male nut are different, however, than in the Speedometer itself. The seller told me the threads never changed, but it clearly does not fit and this was confirmed by my Speedometer shop. Has anyone run into this? If so, what have you done? It's hard to imagine that Dennis Carpenter and others have not gotten lots of complaints over the years if this was a thing. I have three speedometers all from a 1940 and I've tried the new cable in all of them with the same negative result.