From the early 1930s there were only two sizes, Hue. Large and (later on) smaller. See https://aafradio.org/garajmahal/flex_drive_cables.html for the dimensions and a lot more.

Everything except the ARC produced gear used the large one, including the ARB and RU receivers. The confusion is usually over the Army and Navy terms for them (MC-*** versus the more complex Navy numbering system), compounded by often nothing but manufacturer numbers like your S. S. White example. The "large" design even had a square drive, which I mentioned on the web page above.

- Mike KC4TOS

On 5/2/2025 9:35 PM, Hubert Miller wrote:

So, okay, the MC-136 is for the MN-26 and military RDF standalones.

What about the S. S. White 9107 ?

“Large and small” descriptions are not real helpful to me.

Thanks to all respondents however.

-Hue Miller

MC-***