Station 129
Station 129 has an issue 2 board, so it's my oldest Beeb. Many of the chips date from the second quarter of 1982 or earlier, although it looks like the disc and Econet interfaces were added later as the date codes are quite a bit later.
Some standard Model B parts are socketed, such as the second 16K of RAM, which often means an A-to-B upgrade but I believe it was production practice at the time of issue 2 to socket these chips even on factory Model Bs.