Part number 43410-341-700 (superceeded 43410-300-020). Good used OEM rear brake rod. Also includes the small fitting, part # 95015-32001.
Listed to fit:
CB750K A MOTORCYCLE, JPN, VIN# CB750-1000001
CB750K A (76) MOTORCYCLE, JPN, VIN# CB750-2540001 TO CB750-2575894
CB750K1 A MOTORCYCLE, JPN, VIN# CB750-1044650
CB750K2 A MOTORCYCLE, JPN, VIN# CB750-2000001
CB750K3 A MOTORCYCLE, JPN, VIN# CB750-2200001
CB750K4 A MOTORCYCLE, JPN, VIN# CB750-2300001
CB750K5 A MOTORCYCLE, JPN, VIN# CB750-2500001