FWIW a local radiator shop also did speedometers I bought some parts from him and picked his brain. Seems GM used the same speedo guts for decades and he had some NOS parts from sometime in the 70s. I used them on my 51 speedo. But eventually, something else went wrong with it and his shop had become a hamburger joint. So I bought a new repro one but I don't remember from whom. It has worked fine for a decade but do check for accuracy before you put it in (see my other post for method).
