I have an 85 El Camino with just your basic gauges. It had speedo, oil pressure light, gas gauge and big clock. The other 3 were blacked out by the factory. I recently bought a gauge cluster out of an 85 Monte Carlo. It has all the gauges and they have all the needles. My question is im not sure what I need to do and or get so they all work. My speedo is off by 10mph, my gas gauge doesn't work most of the time (always reads full), tach, volts and temp don't work at all and the oil pressure gauge is going from a light to an actual gauge. What I've been told is I need sending units for those things. I have the Chilton,(not sure how much use it will be since it not the original engine for this truck. I believe it came out of a old Chevy pickup because the wiring harness has the hookups to plug in a quadrajet M4ME. Which was not standard on any El Camino I've heard of but was on the chevy pickup. Would also make since that it came from a truck since the guy I bought it from had a 76 chevy pickup dragged out in his garage. When I go through the Chilton I see temp switch, oil pressure switch. Is a switch the same as a sending unit and to get what I need, I order my stuff from rock auto, what exactly am I looking for? Thank you.