if you get the harness that goes with it then there isn't much to write about - and since that stuff isn't in the non sr5 harness (keep the dummy in your main gauges) that isn't related. You need to go get a sending unit (not for a light) for the oil and put it in another spot in the block and run a wire from it to the gauge. There will also be a ground and backlight.
The volt just needs +. You probably want to tie into the factory dash lighting so you get the dimming though..
BTW I have an 83 SR5 gauge for sale in the classifieds