There is no such Fairchild airplane called "Rancher". The model 24 is powered by either the Ranger 6-440-C series 175/200 hp engines or the Warner 145/165 hp radials. Other than the RAF designating the lend lease UC-61 (F-24) as Argus, there was never an official name assigned by the manufacturer.

FMI: http://www.fairchildclub.com/ and http://groups.yahoo.com/group/fairchildclub/

Alternately, search the web for "Fairchild 24". There are a large number of sites dedicated to this aircraft.