Steering servo plugs directly into rx. Throttle plugs into +1 unit & the corresponding lead out goes into rx for for/rev. The other lead from +1 unit goes into rx to operate dump.
Don't need 4chs, it's just a radio I had on hand to use.
When little kids come with their parents to see my layout, I give them this trk to run around with, it's virtually indestructible & easy to drive. When they try to drive somewhere they shouldn't & do something like pull a power turn or ramp it,
I holler at them, "drive it like a real one is suppose to or park it!", boy their eyes sure get wide!!!
Here's a vid showing the bellydumps last night... weather not so friendly again.
https://www.youtube.com/watch?v=6HczfGfyWIg