I have a never used Maslow kit that was purchased in March of 2018. The kit includes all original parts - most never opened. The kit includes the metal ring.
The Z-Axis has the .375 in, ⅜ in coupler that works with the rigid R22002.
I’d prefer PayPal. Feel free to message me through the forum for more details.
I bought the kit but ran into some medical issues that has prevented me from using it. Hopefully my loss can be your gain.