[George16]

The 5625's has about 164 oz.in of torque and should be adequate for your truck. In fact, it should be able to center itself easier when it's running compared to when the truck is at a standstill. Less torque is needed when the vehicle is in motion.

If I were you, I'd try with just a single servo. Two servos are more of a liability and headache if they are not synchronized together. It seems to me that they are fighting/canceling each other a little bit.

Great-looking truck you got there! Don't be scared in running it up to speed. Just find a wide and clear area to run so you can minimize the chance of hitting something.