Leo Fender was always experimenting. As a result, the amplifiers faced changes or upgrades - either cosmetically or electrically - much more often than there were new official models introduced. Towards the end of the "Brownface" era Fender was already switching to black tolex in their amps. Technically, however, the amps still represented the previous "6G generation". This amp is one of those made during this interesting period that began in mid-1963 and lasted for an year or so. Inside, it's a 100% genuine 6G2 Princeton, only with a black covering and white knobs - hence the moniker Blackface White Knob (BFWK). A few of people also call the amps of this era "Tuxedo" Fenders.
At least three different speakers were used in 6G2 Princetons. Fender Discussion Page user "DuncanMaynard" has gathered the following information: August 1961-March 1962 Oxford 10JB-14 AlNiCo, May 1962-December 1963 Oxford 10J4 ceramic, July 1963-December 1963 CTS AlNiCo. There may be some overlaps. Also, according to him, the changeover from brown to black tolex occurred around November 1963.
Specifications
Tube configuration
Serial numbers:
Chassis: P06578
Stamp on top of chassis (between output tubes): AB4963 (1963, week 49)
Stamp inside chassis (between bias circuit and mains transformer): TC4963 (1963, week 49)
Another stamp inside chassis (between V4 and V5): A.E.
Stamp on mains transformer bottom: TC4963 (1963, week 49)
Stamp inside cabinet bottom: AB4763 (1963, week 47)
Tube chart: ML (December 1963), Production #19
Mains transformer: 125P1A, 606337 (1963, week 37)
Output transformer: 125A10B, 606339 (1963, week 39)
Speaker magnet: 137-338 (CTS, 1963, week 38)
Speaker frame: AB4763 (1963, week 47)
Speaker cone: 1002-1