This is the OEM Mitsubishi brake proportioning valve that is mounted on the lower-middle part of the firewall. While it is not common for them to need replacing, they do occasionally fail.
You choose depending on whether the vehicle is equipped with ABS anti-lock braking system.
There is a single bolt that holds it to the firewall - this is available separately if you need it.
The ABS Proprotioning Valve has been DISCONTINUED and is no longer available, but we do offer the 3SX ABS Delete Kit.