| Model number + Sears catalog season (the primary Silvertone dating key) | 1949-1968 (Danelectro/Sears amp line), older Valco-built models 1940s-1960s | 18 | Dates the MODEL RUN, not the individual unit: an amp built in the last year of its run and one built in the first look identical by this key alone. Co |
| Chassis / service number 185.xxxxx (Danelectro) | Danelectro-built Silvertone amps, roughly 1949-1968 | 5 | IDENTIFICATION ONLY — it is not a date and not a serial: the same plate number appears on every example of that model (e.g. 185.10201 is shared by the |
| EIA component codes (speakers, transformers, pots) | 1940s-1968 | 3 | Component codes date the PART, not the amp: a replaced transformer/speaker/pot can be newer than the amp. Upper-bound rule — the amp is not older than |
| Valco-built Silvertone amps (use the Valco V/X/T/G table) | 1940s-1968 | 1 | Brand cosmetics decide nothing — Valco built the same chassis for 5+ house brands. |