Back in 2017, I bought a 50 with a spike bayonet. I shortly after posted it in SKS-Files forum and it started a debate if there were actually spikes installed on 50's. It was only later that documentation on a different post that mention spikes of 50's. When talking about rarity, I consider it on the list as it was only manufactured for 32 days or less in 1950. If you look at the last couple paragraphs of the post below, you will see.
https://www.patreon.com/posts/36996477
https://www.patreon.com/posts/36996477