They had 4 numbered oscillating engines, A #6 is the vertical and a modified version is being cast by Myers engine works out of Ohio.
Yours looks to be a number 2 it is missing the siphon pipe/pigtail and steam gauge. They were used mostly on the free standing or smaller push wagons/carts for the peanut roasters with popcorn attachments. Say the #2 wagon which was their cheapest wagon that they built. But you could get the #2 wagon with a #1 Horizontal for more money.
just like the same wagon came with standing room, without standing room but a drivers seat, or with out wheels and mounted on legs for in store.
The biggest problem is the small steam engine like Cretors was the fractional horsepower motor of the day. They were made by every small machine shop and were used on everything from dentist drills,sewing machines and laundry equipment etc. You could even buy the casting from mail order and machine them so the machine shops would buy the same casting kits and thus accounts for another reason the are so many slight variations.
Cretors made and sold them to any body that had cash before he worked out the peanut and corn popping equipment. He then would buy the engines from anybody that had them ready in stock as he needed them to fill orders. After Cretors quit making their own. Thus accounts for the many slight variation in the Cretors peanut roasting engines. Not counting the fakes that have been made over the years.
Myers also had a 1/2 scale brass casting kit along with the modified vert#6. They may or may not have the full size #1 casting kits. Due to the minimum casting charges and cost of the kits before any work was done on them.
The Canadian company that was the sole Cretors approved company to make new old style Cretor's wagons for the Disney parks, the hotels and others. Had fake engines in them and they were chromed not nickel plated, as the originals. due to fire dept reg's they were reverse drive by the chain drive by an electric motor. No boilers or steam in the ones in Euro/Japan/Disney parks and hotels or the ones in the malls in the US or Canada.
Hope this answers some of your questions.