The Mazda RX7 sure is a special car. I have a friend that idolized this car back in the day (late 90s early 2000s) and he was not alone. Apparently this car still has a big fanbase.
I was only able to find Japanese websites on this, and one particular one mentioned the connector of this fan. However, I had to use the Google translate to get an idea.
FD3S 電動ファン変換カプラー | ドゥー・エンジニアリング・スタッフブログ (do-eng.com)
It seems that they custom made these connectors. Replicas of them rather.