Wanted to share my research I just did for sourcing the 4 pin Molex KK connectors used on the SO3 steppers and controller board. I am upgrading the cables to shielded 22 awg so needed these. I found some incomplete info here and there, so hope this helps someone.
Crimp Terminal Housing (female): https://www.mouser.com/ProductDetail/538-09-50-8043
Crimp Terminal (pins): https://www.mouser.com/ProductDetail/538-08-50-0106
Header (male): https://www.mouser.com/ProductDetail/538-26-60-4040