Ive never owned a GMC. However, it would not surprise me if most of the 4x4 have the same feature. I had a 1984 little ranger 4x4. I took it out hunting birds on some logging roads etc. I put it in 4Lo and I was amazed, I did not have to touch the throttle. I had a stick shift on that truck. It would not stall and it would reduce power when the going got easy. It was fantastic control.