Microshift Mountain Bike 7\8\9 Speed Rear Derailleur – Cycle Core
Amazon.com : Rear Derailleur, Huazu Bike Parts Gear Shifter for Shimano RD-TZ31-A with Direct Mount/Hanger Mount for 6/7 Speed Mountain Bicycles : Sports & Outdoors
Amazon.com: lundeng OEM RD-TZ31 6/7 Speed Rear Derailleur Direct Mount for Mountain Bike : Everything Else