[ElGracho]

BigRed, that thing you just changed for you oil pressure light is not really a sending unit. It is a swich, on when pressure is low (<5psig) off when pressure is high. The gage from the 78 needs a sending unit that has variable resistance for varying oil pressures. Binary vs analog if that floats your boat (submarine in my case).

Anyhow, you may not need to run a new wire to the alternator. You are looking for a good low resistance connection to your battery voltage when the ignition is on. There are lots of places you could tap into, I would have to look at a specific diagram to see if an existing wire would work. I would most likely look at what was factory on the 78 and try to make the 75 look like that.