Recently on the bay site i seen a few listing for a 1946 lionel motor that fits the 671,2020 726.
Someone looking for a 726 motor would be disappointed because those listed 1946 year 671 motors have the large gear which definitely will not fit the 726 frame .
Look at the picture above poster and the tunnel at the end of the motor where the gear end goes thru the 671 gear will not fit as i tried one day out of curiosity.
I have several 1946 671 turbines not converted to the updated back then smoke unit they run nice but like running Berk a little more.
Hope this helps someone down the rails.