O Gauge has had smoking steam engines for as long as I can remember. I still have some of the pills my grandfather would drop into his 2056, 1656, and 1666 PW steamers and his 4-4-0 General.
Got me wondering why smoking diesels are (to my knowledge) a new thing. Seems like this feature is new in Lionel to Legacy and LC+. I have 4 modern diesels with factory-installed TMCC but no smoke and 2 modern conventional diesels again with no smoke.
Can smoke be added to these modern TMCC diesels? Cost effectively?