IdaD wrote:
I think he's saying 4" - from 16" to 20". I think it're more like 2", though. Mine runs flipped the other way so the kingpin is a couple inches in front of the ball. I doubt it makes enough of a difference in the torque applied to the trailer frame to matter either way, except maybe in some really rare cases.
The distance is 4" not 2" from where the kingpin attaches to the adapter to where the ball enters the adapter socket. The adapter actually has an 8" difference as far as where the fifth wheel is from the cab. Depending on which direction the adapter is installed .