Oil Pressure/temp sender the same unit?

[techspy]

My oil temp gauge isn't working. I found a wire that I think is supposed to be connected to the oil temp sender disconnected. I think a PO had the original sender unit replaced with one that is only an oil pressure sender. I have 2 old OEM senders with both connections but am not sure if they are any good.

So, anyone know how I can test these old sender with a multimeter? Seems these senders are like $250. Anyone know of another temp sensor I can connect somewhere? I wonder if I could connect a temp sensor to the case of the oil pressure sender to get a temp of the oil.

Thanks for any info.