Its found on page 2.16 of the T9 2006 manual as “Strut, Lift, Arm, Loader, TC5/ T5D/ T6/ T7/ T9”. Part number 12056. And page 2.12 of the T7 2007 manual.
My understanding is it is used as a safety device to ensure the loader cylinder does not retract when raised. I’ve found it rattles too much while stored and I had to put duct tape around the ROP to isolate it.