A Lionel 4-4-2 steamer I got on ebay. It needs what I call a motor mount for the DC can motor plus I think there is a gear attached to it that goes between the can motors gear and the big gear between the 2 drive wheels. No numbers on the side of this engine. I got it off ebay without a tender.
I can’t help with identifying the part, Boyd. But let me suggest posting a link to the auction, if it was fairly recent. That might help someone to recognize the locomotive.