This would be the earliest of the 1118s as it has the plain open headlight and NO A / D switch. Red stack, no headlight shell and lightening rod drive rods

Circa 1912-16 the 2nd version of the 1118 had a covered headlight, black stack and a functional A / D switch, also note the automatic coupler on the front of the locomotive - the example below has a hook coupler

Headlight missing, but red stack and steam chest

Not sure what to call this, cab has single window, no operating headlight, straight boiler, but the motor from a 1118 and rubber stamped No. 18. It came with a set of Ives Cars. 

Circa 1915-16 - Same casting as earlier, just rubber stamped lettering -