Lima (actually Lima-Hamilton) built the last four Rotaries and used two Shay-type 3-cylinder engines geared together to power the wheel.
Two for UP in December, 1949. Numbers 075 and 076 (later 9000075 and 9000076)
One for Soo Line in January, 1950. Number X-19
One for Rock Island in January, 1960. Number 95377
ALCO was no longer building steam locomotives so these were built under by Lima-Hamilton under license. The last previous rotaries were three built in Oct-Dec 1937 by the Schenectady works.
Information from
Snowplow: Clearing Mountain Rails by Gerald M. Best. Howell-North Books, 1966.
Brian Norden