T/S Valve id

[breplum]

Probably 80s. Cannot remove thermostatic cartridge. Deep inside looks like a special thin walled socket would be needed to remove a large capture-nut. Something similar to a water heater, element removal tool.
I’ve told homeowner it is not repairable.

 

[Geofd]

Maybe t+s has that tool
symmons has a valve and the seat comes out with a thin wall 1 1/2 thin wall socket

 

[breplum]

Reminds me of Danze, esp. the threaded receiver for the trim