Ya, Mechanical you have to have the lines all the way to the gauge. So ones like oil pressure and what not you would have an oil line in your cab with you. Get the electrical one. I just got an oil pressure and it comes with everything you need except wiring. Pressure sender and all.
Im not sure if they make a mech. water temp? Are you asking what other guages you should get too? The electrical water temp guage comes with everything also. I have both waiting to be installed.
id go with a mechanical water temp gauge if ya can. ya they may be a little harder to run lines to but its not that bad plus they are very accurate and you get a full sweep. to get a full sweep electric gauge you pay big $$$