23W 1x15 piggy-back bass amp — listed in the Spring/Summer 1965 catalog as "The Bass Amplifier".
Marks that can be entered for this maker: Transformer code, Chassis stamp.
Nothing predates 1963; components only push the date later.
Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.
Evidence: Blue Book of Guitar Values — silvertone · Silvertone World — model 1483