Looks like the RRS unit. Reach out to Diona at dionajo@rrsusaonline.com https://www.autorestomod.com/about-us.html they are the RRS dealer in the states. Jeff is very knowledgeable. I was quoted, about to pull the trigger, so many great maverick goodies.
I've done a lot of study of torque arm suspensions recently, mostly in connection with a lot of head scratching I've one over a New Edge Mustang. Torque arms are a really versatile setup with the potential to provide good ride, good bite at the drag strip, and excellent handling.
from Northeastern Pennsylvania - I just have a simple Watts Linkage on my 9 inch an never seen one like yours