4AR and 4AU are interchangeable. Based on the ebauche from A. Schild: AS 1017. 4 3/4''' x 6 1/2'''.
Versions of the AS 1017 were being made into the early 50's, but the design had radically changed.
How about a 4AH??
JP if you have any info on the 4AH that isn't here please feel free to add here: http://www.mybulova.com/node/961