This is a run down list of what parts are required to properly install a Tach & Seperate shift light.
#2 Shift Light
Be careful when choosing a shift light, as different shift lights will require different installations. The shift light in these instructions has a built in RPM activation dial. This is probobly the most easiest/cheapest to install. ($55+)
If you want to use a "mini" shift light, you will require a seperate RPM Activation Module (70+) which will then require RPM "pills" ($30+). If choosing to go this route, you can use the wire routing in this guide to assist in wiring the RPM Module.
You can also use a shift light with the Built in RPM Module, which also requires the RPM "pills"
#3 Tach Adapter
You CANNOT use a tach in your 99-04 GT without one!! You NEED this.
You may also need some extra wiring depending on where you mount your tach & light.