Brake light switch diameter

[Tea]

Hi all,

We have a standard 1971 Traveller and are need of replacing the brake light switch (spade connector type). The replacement that we received looks like a 3/8" thread, however this is too large for the brake union that we currently have installed. Going by my caliper, the size we currently have fitted is roughly 8.5mm (somewhere around 21/64" - 11/32"). These sizes are for the minor diameter - I've never really known whether you should look at the minor or major diameters when looking for the correct size...
Going by ESM, I'll assume our current one is not standard and so where would I be likely to find a replacement from? More information can of course be provided.
I'd prefer to just replace the brake light switch rather than both units.

[Steve Phillips]

I believe it's 1/8" BSP (British standard pipe) although I'm always open to be corrected,

[Tea]

Thanks Steve. The hunt continues!

[philthehill]

The brake light switch threads are 1/8" BSPT (Taper). The threads in the housing are 1/8" BSPP (Parallel).
The threaded boss of the switch is nominally 3/8" diameter.