| Serial plate identification (which era / which maker) | 1966-present | 7 | Check the plate text BEFORE applying the range table: Turntone/Sterling numbers fall inside the vintage ranges even though those amps are from 1985 or |
| Harry Joyce wiring mark and white wiring-date tag | 1971-1984 | 2 | The mark dates the WORK, and the source warns it is not the final manufacture date: 'the date that the wiring crew put on the amplifiers was the date |
| Component date codes ('YY WW' or 'WW YY' on caps / pots / speakers) | 1966-1984 | 8 | 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 |
| Model era table (DR / SE / OL / S / SA / Bulldog / modern lines) | mid-1960s-present | 10 | Era dating only; the serial range table is the finer instrument for the 1966-1984 amps. |