I made the mistake of looking for a replacement thermopile that would fit the small hole on the fireplace coupling. Since my fireplace was manufactured in 1982, no such product exists. I ordered the Honeywell, and simply drilled out the hole in the coupling large enough to insert the Honeywell. It worked like a charm. Did not need to change anything, fool around with any gas connections, and simply plus the two wires where they belong.