Interesting. The only other Rudy I have seen without the extra low C vent is a Bb Soprano, s/n 32903:- http://www.ebay.com/itm/161526154464?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT
Fairly certain I can faintly see the Rudy banner on Ringo's Alto (see also the thread started by jazzbug1 which popped up again today regarding design changes to the Rudy model between 1929 and 1930, proving the continuing Holton creativity and evolution throughout the Rudy banner era)...Sorry to be late to the party....Ringo's Holton doesn't appear to be a RW model at all but a standard Holton with the Rudy type neck. Look at the bell for the name......I just compared it with the saxpics model. The neck had me fooled.