The servo rudder you are looking for is here, all sizes and mounting types are available!
Reference 02UR1802
Brand: ULTIMATE
ALUMINIUM SINGLE ARM SERVO HORN (24T - HITEC) (1pc.) - UR1802
Reference 08293401
Brand: HUDY
ALU CLAMP SERVO HORN - KO PROPO, SANWA - OFFSET 1-HOLE M3 - 23T - 293
Reference 08293408
Brand: HUDY
ALU CLAMP SERVO HORN - HITEC - 3-HOLE M3 - 24T - 293408
Reference 08293444
Brand: HUDY
ALU CLAMP THROTTLE SERVO HORN - KO PROPO, SANWA - 2-HOLE - 23T - 2934
Reference 08293445
Brand: HUDY
ALU CLAMP THROTTLE SERVO HORN - HITEC - 2-HOLE - 24T - 293445
Reference 08293446
Brand: HUDY
ALU CLAMP THROTTLE SERVO HORN - FUTABA, SAVÖX - 2-HOLE - 25T - 293446
Reference 08293449
Brand: HUDY
ALU CLAMP THROTTLE SERVO HORN - FUTABA, SAVÖX - 2-HOLE M3 - 25T - 293
Reference 08293492
Brand: HUDY
ALU SERVO HORN - HITEC - OFFSET 1-HOLE M3 - 24T - 293492
Reference 08293494
Brand: HUDY
ALU THROTTLE SERVO HORN - KO PROPO, SANWA - OFFSET 2-HOLE M3 - 23T -
Reference 08293497
Brand: HUDY
ALU SERVO HORN - KO PROPO, SANWA - 2-HOLE M3 - 23T - 293497
Reference 08293505
Brand: HUDY
ALU THROTTLE SERVO HORN - HITEC - 2-HOLE - 24T - 293505
Reference 02RC15202-BLK
Brand: RC PARTS
ALU CLAMPING SERVO HORN BLACK (25T - 19mm) - RC15202-BLK