Whats the difference between mechanical & electrical guages? Is one more accurate than the other? I need a trans temp guage for the new tranny, but don't know which to get.

 

Mechanical sender, you have a copper capillary tube
that has to not be kinked and can't be lengthened
if need be; it's sealed fluid/vapor. But you also don't
need to do any extra wiring for power / ground, just
pick up the dash illumination feed for the little light.

Electrical vs mechanical gauge, probably not enough
accuracy difference to worry about for a "health
monitor" (not like calibrated science) application.

Mechanicals seem to be cheaper initially and reliable
enough, but I would not have a mechanical oil pressure
gauge or anything where a fluid line break, would cost
you motor or carpet damage.