My wife's Expedition recently started having erratic behavior from the oil gauge. I didn't believe it was an oil problem because she drove it about 50 miles before telling me about the problem.

So after some research it looks like the most likely problem is the oil sending unit, and that this is located just behind the filter? I also read that this part should only cost $10-20, but the problem is I couldn't find any stores online that had the part listed.

First question is does my diagnosis sound right about this problem, or is there something else I should be looking for?

Second question is does anyone know what online store might carry the sending unit so I can get one ordered and fix this problem?

Thanks in advance!