This is a Cub Cadet Models 1015 1020 1315 1320 PTO Idler Arm Bracket. This is a New Old Stock part. Part No. 703-2100  (2b)

All Models:

1015 (138-200-100, 131-200D100, 139-200-100, 130-200-100) - Cub Cadet Lawn Tractor (SN: 126001 - 207400) - PTO Drive
1020 (138-210-100, 131-210D100, 130-210-100, 139-210-100) - Cub Cadet Lawn Tractor (SN: 126001 - 207400) - PTO Drive
1315 (139-222-100, 130-222-100, 131-222F100) - Cub Cadet Lawn Tractor (SN: 147008 - 207400) - PTO Drive
1320 (139-232-100, 131-232F100, 130-232-100) - Cub Cadet Lawn Tractor (SN: 147008 - 207400) - PTO Drive