Heres what you got:
s9451
• Speed: .11 Sec/60 Degrees @ 6V
• Torque: 127.8 oz-in @ 6V
s9350
• Speed: .12 Sec/60 Degrees @ 6.0V
• 139 oz-in @ 6V - 10.0 kg-cm @ 6V)
5998TG
• Speed (6.0V): 0.19sec/60°
• (6.0V): 249.96oz/in.
I would use the 5998 on the steering and 9451 on the throttle. The 9350 is almost the same as the 9451 so it does not really matter. But thats what it looks like to me.