I have an 80 4x4 with a factory tach..no gauges needed. I put a tach in my 84. I ran an oil pressure gauge in my 85 when I first put the motor together. I didn't know It was so hard to find a metric to standard fitting for it.
Sure, the numbers shown on the gauges don't represent anything other than what they cycle to when key is turned, once running they go to the actual ressures, temps ect.
top row L-R water temp, oil pres, vac-boost/air fuel, fuel pres, volt
bottom row, oil temp, outside air temp, tach
and over to left of pic you see a little red blue tint, thats a blue shift light with red digital tach inside, plus still have the stock cluster gauges and idiot lights. I like to keep track of whats goin on under the hood
The gauges are cyberdynes blue ice models, the boost gauge is a glowshift but as of today it was removed and replaced with another cyberdyne boost gauge, didn't like it, and it didn't match as well as I hoped, plus it had some problems. They were bought individually. The tach is autometer, and the shift light is a stewart warner, all toll I have around 750 tied up in the whole setup.