[hk20000]

electronic gauges:
you have a sensor of some kind already plugged to the oil/water you are trying to read temp from. Basically tap a wire from the sensor you get a reading

mechanical guages:
You DON'T have a sensor on the spot, the gauge comes with one, you have to plug a hose (for pressure) to the pressure you are trying to sense.

for an AE86, both water temp and oil pressure have seprate sensors, so electronic guage will do just fine. Check the correct current tho, that I dunno how.:shakehead