Roto Track Arm?

I'm looking for a replacement arm that can attach to a roto track. I've already replaced the inner track parts, but also need to replace the outer track. I see the outer track and the track slider (links below), but I don't see anything like the single arm that attaches to the window per the photo (it's the brass-colored arm, not the silver-colored one)

Roto-Slider/pd/Replacement-Window-Operator-Accessories/39-541
Roto-Casement/pd/Replacement-Window-Operator-Tracks/39-542

Any ideas?

Thanks!