what's the difference between mecanical and electic gauges

[86LX5liter]

Let's say for instance you have an oil pressure gauge. An electrical one would use the stock sending unit, and electric wires to send the information. Now, if you had a mechanical gauge, you use a different adapter on the motor, and a capillary tube going directly to the gauge where it measures the oil pressure. An electrical water temp gauge uses the stock sending unit in hte intake manifold, where a mechanical has a little thermostat, and capillary tube that goes to the gauge. got it?

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12.54 @ 110.90
1.62 60'
best with old car, will let you know once i finish the transfer to the new to me car

I have pictures now, and here are the specs