Atwood single sense spark probe. If you're existing probe has 3 prongs and 2 wires, this is the replacement. You may then also need to replace the control board. If that's the case, then order kit # 91504.
Used in the following models of Atwood RV waterheaters: GCH6-4E, GCH6-6E, GCH6-7E, GC6A-7E, GH6-6E, GH6-7E, GHG-8E, G6A-6E, G6A-7E, G6A-8E, GCH6A-7E, GCH6A-8E, GCH6A-9E, GC6AA-7E, GC6AA-8E, GC6AA-9E, GCH10A-2E, GCH10A-3E, GC10A-2E, GC10A-3E, G10-1E, GH10-1E, G610-3E, GH610-3E, G10-2E, G10-3E, GC10-1E, GC10-2E, GH10-2E, GH10-3E, G6A-2E, GH6-3E, G6A-3E, GH6-3E, GH6-4E, G6A-4E, GCH6A-10E, GC6AA-10E, GC10A-4E & GCH10A-4E.