Jim Wilkins wrote:

Dos it back up to a closet where you could cut an access hole and fit
a cover?


No, shower and tub are back-to-back, plumbing is in the common wall
and both surfaces are tiled.

I suspect a lot of these valves were used in the '50s and '60s and
quite a few of them are still in service. If I knew what they're called
it's likely I could find a wrench, or at least what the wrench looks
like.

I don't have any machine tools except a lathe, so cutting a pair of
accurate wrench flats will be a "file and fit" proposition. Using the
lathe to form a pilot hole that fits on the valve stem/bonnet will
ease the fiting problem somewhat, but a purchased wrench of the correct
type is much less likely to damage the valve.

Would posting a photo of the valve bonnet help with identifying it?
I thought somebody would recognize it by the description.

Thanks for posting,

bob prohaska