older lennox elec. Furnace. Ser. no. 5879h 13784 would like to wire basic 2 terminal thermostat. Which wires to couple? Red=heat relay1 orange=heat relay2 yellow=tranformer blue= transformer black=multiterminal conn brown=same multiterminal conn. Don't recognize multiterminal conn. Seem to be made of bakelite

On most furnaces the R=RED and the W=WHITE are the terminals that are used to activate the heat circuit.