You are not dense. If someone had a stock of those 51-59 spindles, I bet they could sell 500 pairs in one year.

https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=1054781#Post1054781

Post a want ad in the Swap Meet. Make sure you specify that you want a usable pair.

I bought a NOS pair on eBay about 15 years ago but have not seen many since then.