This is a follow-up.
Although the great list of SUNPAK flashes (above) was not helpful to me -- because I was looking for tiny flashes -- I've solved my problem.
The SUNPAK Auto 121C and Auto 121S are the smallest flashes that I've found that have both manual and automatic exposure modes -- and a hot shoe. There are lots of smaller flashes, of course, but they don't meet my requirements because they either lack automatic exposure control, lack manual exposure control, are dedicated to a particular camera, lack a PC connection, or other limitation.
It took me a while to get a Auto 121C and a Auto 121S -- in working condition at a good price -- but I now have both. The photos that I've seen of both make them look to be the same, but I figured there would be some difference.
((FYI, there is also a plain 121 model, but it's larger than the Auto 121C and Auto 121S. There are also NON-auto 121C and 121S models-- which are the same, but with only manual exposure mode,and lack the "AUTO" in their names.)
It turns out that the Auto 121S and Auto 121C are exactly the same in terms of body shape & size -- and features & operation. There is one small difference that might explain the two different names. The bottom of the plastic flash shoe is stamped with a serial #. On the Auto 121C there is only the serial #. Mine starts with "20XXXXX". On the Auto 121S, in addition to the serial # (mine starts with "40XXXXX"), it is stamped "HONG KONG". So the "S" and "C" might just mean different factories.
Here they are on a Minolta MG-s and 16II -- a perfect match for a small camera. Guide # of 46 (ISO 100 in feet), using two AA batteries. Weighs 3.2 oz. 2.6 x 2.4 x 1.6".