The 6K can be used with several types of joysticks.
The JS6000 (now discontinued) is a 0V to 2.5V joystick. In order for this to be used with the 6K, a Custom Product needs to be requested that has an extra connector on it. This extra connector has analog inputs designed to be used with a 0V to 2.5V joystick.
Other types of joysticks include 0V to 5V, 0V to 10V, +/-5V and +/-10V. Any of these can be used with the 6K's expandable I/O module, the EVM32 (now discontinued), and its Analog Inputs.