Thanks for the pics Jaros44sr. That helps a lot. I'll be working on my Blazer tomorrow so I'll be able to investigate what is there.
So I will need an electric sending unit. I'll try Pep Boys or some other parts store.
Do I need another wire to complete the loop or is the green wire the only wire I'm dealing with?
As for the vacuum, I was told by Gary Terry of
www.cs-m.com that I need to run a tube from the gauge through the firewall to a hose the goes from the intake manifold to the A/C. Then tap into the line by adding in a "T". I was just curious if anyone had some info about it while I was asking about the temp. gauge.