New genuine Kubota pto shift arm, part number 6C040-18712.  This part fits the following.

B1700D (4wd)
B1700E (2wd)
B1700HSD (Hydrostatic Transmission, 4wd)
B1700HSE (Hydrostatic Transmission, 2wd)
B2100D (4wd)
B2100E (2wd)
B2100HSD (Hydrostatic Transmission, 4wd)
B2100HSE (Hydrostatic Transmission, 2wd)
B2400D (4wd)
B2400E (2wd)
B2400HSD (Hydrostatic Transmission, 4wd)
B2400HSE (Hydrostatic Transmission, 2wd)
B2410HSD (Hydrostatic Transmission, 4wd)
B2410HSDB (Same as Hydrostatic 4wd, but includes Bi-Speed turn)
B2410HSE (Hydrostatic Transmission, 2wd)
B2710HSD (Hydrostatic Transmission, 4wd)
B2910HSD (Hydrostatic Transmission, 4wd)
B3200HSD (Hydrostatic Transmission, 4wd /Rops)
B3200HSDWO (Hydrostatic Transmission, 4wd /Rops/Without loader valve)
B3300SUHSD (Hydrostatic Transmission, 4wd /Rops/ Special utility)
B7400HSD (Hydrostatic Transmission, 4wd)
B7410D (4wd)
B7500D (4wd)
B7500DTN (Dual Traction 4wd / Narrow)
B7500HSD (Hydrostatic Transmission, 4wd)
B7510D (4wd)
B7510DN (Dual Traction 4wd / Narrow)
B7510HSD (Hydrostatic Transmission, 4wd)
B7510HSDTR (Hydrostatic Transmission, 4wd / Turf Special)
B7610HSD (Hydrostatic Transmission, 4wd)
B7800HSD (Hydrostatic Transmission, 4wd /Rops) - PTO GEAR SHIFT LEVER [MID PTO TYPE]
B7800HSD (Hydrostatic Transmission, 4wd /Rops) - PTO GEAR SHIFT LEVER [EXCEPT MID PTO TYPE]