I was trying to revive a few futaba servos that I had, but I only had a few of the FUTM3500 Replacement Gears left, and also the problem with these first gears is that their plastic and the rest of the gears are metal

Well, I also had a Ko Propo lying around so I took it apart and what do you know, the first gear is the same size as the futaba servo I have.

So I put everything together and it works fine.

I can't find the Ko Propo Servo gear set for the 2366 but the 2368 1st gear looks to be the same, so this is a solution for those that have the Futaba S9351, S9155, S9451 servos lying around.  It looks that Amainhobbies has the 2368 gear set in stock, but you might just try calling Ko Propo also.

Good work.

I had used the same gear from a hitech 645 and put it in an ace becouse the ace is all plastic and the hitech the outer is plastic but the inner gear is metal.