Which is the little sheet metal sight? I thought that was the no. 5.
Yes, that is the No 5, It was replaced with the better No 10 (a direct replacement) and then the No 10 was replaced with the No 15, which is very similar, it had different mounting holes. The No 10 sits completely on the receiver and the No 15 has a longer base and hangs over the rear about 1".
The 23-AA & Model 19 (1933 version) are first listed in catalog #67 from late 1933 or 1934. The Model 19 listing says it has the "new designed No 10 Savage aperture type sight". (A wholesale catalog dated August 12, 1933 does not have any of these listed.)
Looking at parts catalogs the No 10 is first listed in the 1934 which is also where the 23-AA auctioned guns are first listed , The No 15 is first listed in 1937 so the No 10 was only used on the Model 19/1933 for the first couple years.
