Dear Mr. Butler,
11541 is not listed, and is neither a normal nor a re-issue U67. So, the connector bit was presumably a spare part. But, 11541 was a used for a U87, 1969 to Gotham, and for an i-version, = XLR. Normally these numbers were not doubly used. Some question remains...
Best regards, Martin Schneider Neumann Mic. Development