The neck with the serial number A2357D R seems rather unique, and Dan informed me that "any serial number followed by the letter R was a reject much like a Gibson factory second.It usually refers to some minor flaw in the cosmetics of the instrument".That fourth Magnavox tube was accidentally broken during preparation for the photo shoot.I viewed the new old stock Made in USA G-T 7027A as a better replacement choice than other available off-shore tubes.A note about these tubes: Three are original 'Made in USA ' Magnavox tubes.The fourth is a NOS 'Made in USA ' 7027A zero hour Groove Tube.As a means of quick reference, guitar necks alone can be approximately dated by the serial number on them.While this is by no means an 'official listing' it's pretty close and it's listed here to help sort through at least some of the mystery and confusion.
The bass guitar seen here has a serial number of D1255A which makes it an early 1970 model.
Pre Amp Tubes: V1 12AX7A, V2 12AX7A, V201 6K11, V202, 6CG7, V203 12AX7A, V3 12DW7, V4 12AU7A.
Dimensions: Width: 27"; Height: 10¼"; Depth: 11½"; Weight: ~40lbs.
The serial numbers always ran consecutively, and according to Dan the actual production models "began with number 100." Using this information, the guitar neck numbered A204D is actually the 104th guitar off the standard production line.
Apparently anything prior to A100D was some kind of prototype, or was made at a time prior to the actual production line.