There are FT-243 and FT-241 crystals; they have the same form factor,
but the FT-243 has a front plate that comes off, while the FT-241
opens from the bottom. In the FT-243, the quartz plate is not silver-
plated and soldered to the connector pins; in the FT-241, it is.

Both FT-241 and FT-243 crystals will fit in an octal socket.

International Crystal Manufacturing once sent me a little poster with
drawings of all the different standard crystal sizes including many of
the older ones. They may well have it on their website.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."