You need a hydraulic solenoid about 2000psi and a couple of switches. That is all. You can buy a kit, or make it up yourself. Indicator lights are a bonus.
You need one arming switch, a simple on/off 12 volt item; and a momentary-on, that you can install on your shifter.. I installed a third switch in parallel with the momentary, that I use as a hill-holder, leaving my right hand and right foot , free, as in not on the brake pedal. If you have a manual trans, you will find that very handy, especially when starting off uphill from a stoplight.
