Kyle Perkins asks:
Here’s pics of my recent S-6. It sounds incredible. The label reads 1658 but the penciled in # below the label reads 1686. Can you explain the different serial numbers?

Here’s my supposition, not based on any documentation, but it makes the most sense to me and I expect it’s pretty close to reality.

When a build order came down, the shop personnel would pull parts for the instrument from stock and mark the back with what I call the build number, referencing that order. After assembly and major finishing the inspector would apply the ID label with the serial number. These numbers are usually the same, but for various reasons a given instrument might move through the process more quickly or slowly than expected, and the numbers may not match in the end. This doesn’t show up often, but it happens, more often in the early days, when shop procedures were still developing. As an example, in the span of #s 1459-1659 we currently have 17 basses with enough documentation to show that four have mismatched numbers, a relatively high ratio.

The build numbers disappear at about #46800, in mid-1963, coinciding with a switch from handwriting to a rubber stamp for serial numbers.