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 04SRT-TRX7
Brand: SRT
2 holes 24mm 25T SRT steering servo horn with offset - SRT-TRX7
Reference 08293503
Brand: HUDY
ALU SERVO HORN - FUTABA, SAVÖX - 3-HOLE M3 - 25T - V2 - 293503
Reference 08293403
Brand: HUDY
ALU CLAMP SERVO HORN - FUTABA, SAVÖX - OFFSET 1-HOLE M3 - 25T - 29340
Reference 08293493
Brand: HUDY
ALU SERVO HORN - FUTABA, SAVÖX - OFFSET 1-HOLE M3 - 25T - V2 - 293493
Reference 08293491
Brand: HUDY
ALU SERVO HORN - KO PROPO, SANWA - OFFSET 1-HOLE M3 - 23T - 293491
Reference 08293509
Brand: HUDY
ALU THROTTLE SERVO HORN - FUTABA, SAVÖX - 2-HOLE M3 - 25T - V2 - 2935
Reference 08293407
Brand: HUDY
ALU CLAMP SERVO HORN - KO PROPO, SANWA - 3-HOLE M3 - 23T - 293407
Reference 08293501
Brand: HUDY
ALU SERVO HORN - KO PROPO, SANWA - 3-HOLE M3 - 23T - 293501
Reference 08293495
Brand: HUDY
ALU THROTTLE SERVO HORN - HITEC - OFFSET 2-HOLE M3 - 24T - 293495