I had to replace the original propane leak detector in our 2004 rig a few months ago. The company that made the original white pastic detector here in So Cal went out of business. The brown one sold as a direct replacement came with two wires instead of three and was physically smaller than the original one. I had to epoxy some pieces of wood into the hole in the cabinet for the new unit to fit.I just connected the red and black wires to the existing red and black wires leaving third one disconnected. Check to make sure power to the detector stays on with auxiliary/house battery switch off and check operation per the directions.