where is the oil sending unit?

It is on or next to the oil filter housing at the lower passenger side of the engine. Make sure the oil filter is not loose or the oil drain plug is not loose but do not allow he engine to run if there is less than a quart of oil in it . If you are loosing oil as quick as you say it is obviously oil that is leaking under pressure. The oil filter, oil pressure switch (and I think their is an oil cooler just above the filter on that engine that has a O-Ring that gets brittle over time and can cause a pressure leak) would be the first places I would look. There is a company that independent auto repair shops buy their information from that the same information inexpensively to do it yourselfers. The information is year make and model specific repair procedures, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online