I am replacing my wall oven with a range (stove/oven combo). My wall oven had two #6 wires and one ground in the receptacle . Both are Black, and one has red triangles on it. They both go into the breaker box, the ground wire to the grounding bar, and the solid black wire and black wire with the red triangles both go to the hot side of a double breaker 50 amp switch.  My new stove comes with a 3 wire plug, Red, Black and white neutral, as well as the ground wire. I know normally I would run red and black to the hot lugs in the plug, and the neutral white to neutral, then obviously the ground to ground. But with only having two hot wires and a ground wire in my receptacle. how do I wire the new plug???