It's in the ancient caves tile set! 😃 Sorry for the confusion
Viewing post in The DARK Series - Apocalyptic Highway comments
Haha, I found it there late last night organizing the files from the two bundles. You might want to add that to the descriptions of the packs where applicable. I've seen the question asked more than once on different pack pages.
Btw, while I am a long time engineer this is my first time attempting to build anything on the art side. Do you use Tiled or is there some other tilemap application I should know about?