I thank John for the information about the Silvertone.
«In about late 1964 my parents bought me my 2nd clarinet. It was wood and I believe they ordered it out of the Sears catalogue, where they had purchased my first one, a metal one, a few years before. The wooden Silvertone had a decal on the bell: Silvertone. … [which came off.] So the instrument is bare of all identifying marks - except for a serial number, stamped on the upper joint only: 2525, and underneath: 61557.»
I would guess this to be a later Malerne product, even though it does not have some characteristics of the older ones I have reviewed. It does not have the pin in hole left pinkie keys.