The servo rudder you are looking for is here, all sizes and mounting types are available!
Reference 04SRT-TRX5
Brand: SRT
2 holes 25T SRT steering servo horn - SRT-TRX5
Reference 04SRT-TRX6
Brand: SRT
2 holes 25T SRT steering servo horn with offset - SRT-TRX6
Reference 08293406
Brand: HUDY
ALU CLAMP SERVO HORN - FUTABA, SAVÖX - 2-HOLE M3 - 25T - 293406
Reference 08293499
Brand: HUDY
ALU SERVO HORN - FUTABA, SAVÖX - 2-HOLE M3 - 25T - 293499
Reference 08293503
Brand: HUDY
ALU SERVO HORN - FUTABA, SAVÖX - 3-HOLE M3 - 25T - V2 - 293503
Reference 08293493
Brand: HUDY
ALU SERVO HORN - FUTABA, SAVÖX - OFFSET 1-HOLE M3 - 25T - V2 - 293493
Reference 08293506
Brand: HUDY
ALU THROTTLE SERVO HORN - FUTABA, SAVÖX - 2-HOLE - 25T - V2 - 293506
Reference 08293409
Brand: HUDY
ALU CLAMP SERVO HORN - FUTABA, SAVÖX - 3-HOLE M3 - 25T - 293409
Reference 08293496
Brand: HUDY
ALU THROTTLE SERVO HORN - FUTABA, SAVÖX - OFFSET 2-HOLE M3 - 25T - V2
Reference 08293404
Brand: HUDY
ALU CLAMP SERVO HORN - KO PROPO, SANWA - 2-HOLE M3 - 23T - 293404
Reference 02UR1804
Brand: ULTIMATE
ALUMINIUM DOUBLE ARM SERVO HORN (23T - SANWA/KO/JR/AIRTRONICS) (1pc.)
Reference 08293403
Brand: HUDY
ALU CLAMP SERVO HORN - FUTABA, SAVÖX - OFFSET 1-HOLE M3 - 25T - 29340