I have an Avalanche XTE so its basically the same truck but electric.
When I broke my servo steering horn I replaced it with a Axial Aluminum Servo Horn (25T) it has worked great ever since. Well I did break the original servo horn in about 10 min after I started driving it the first time.
I also replaced my servo twice, the latest one was a Savox SC-1256TG, the one before the 1256 was a weaker server made by the same company. I needed the extra torque for turning the wheels in grass. If I break this one from over stressing it I might have to upgrade again.