That photo was taken when Reading T-1 2102 was running on the C&O Greenbrier (Durbin) Branch to the Cass Scenic Railroad - in the 1970's, I think. I hadn't noticed the face in the smoke but when I see a Reading T-1 I don't look for anything else. I'll dig around and try to find that post card but this one looks authentic to me.
Someone would have to track down this post card in the first place and then Photoshop the face in the smoke. I suppose it's possible but it seems more work than reward.
It's listed as a post card. The moment someone would retouch the smoke the photo would have to be printed on suitable (aged) paper. The back (mailing) side would have to be printed, too. That would take time and a lot more $$$ than the price of an old post card.
Just my two cents.
