The standard servo on my Ridgecrest was the AS-3, and that's what I put on my home built scx-10.

I just put the Savox on the jeep, as part of the rebuild, because the Hi-tec wasn't cutting it on the rocks with the heavier weight. The SA1231-S has 444oz of torque compared to 164oz on the 645mg. Don't get me wrong, the Hi-tec works great for a lexan bodied scaler with 1.9 or 2.2 tires, and it worked fine for the 1/6 Jeep, but as I added more scale items, steel bumpers, rollcage, and 2 - 12" dolls, the steering suffered by not being able to steer unless the vehicle was moving. I have not tested it yet because I'm still in the process of the rebuild.