Determining if car has O/D

[Bob Hill <oldcars@newt.vallnet.com>]

Is there a way to determine if a car is an O/D car without driving it?  I
referring to the earlier models that had the switch on the wiper stalk.  I
assume that the engine number would tell or something on the car?  Pardon
my ignorance on the subject but would like to know if it is possible to
tell if a car was originally a O/D car or if it has been added and vice
versa.

Thanks

Bob

79 MGB
77 MG Midget
74 MGB GT
97 Jaguar XJ-R