[JensR]

As I quoted above from Scale 4x4:

"However, if you open up your radio and switch the wires that go from the 3 position toggle switch to the 2 position switch, you will have a "TRUE" 3 position and a 2 position."

Worth a try?

Also, if all else fails, you can install end-position switches to the bed. Then you only need two positions, as the dump bed will stop when the end points are reached. You cannot stop the dump bed in between, though, which is a bit of a downer admittedly.

So, you have several options.

One of them is to sell the radio and get a Turnigy 9x, which is a 7-and-a-half channel radio (7 proportional and one on-off) plus it has a large LCD screen for setting it up.