Please identify this Grohe 3/4 inch shower valve from 80's or 90's.

[RickCl]

The valve in this Grohe 3/4 inch shower is starting to go out. I need help identifying it so I can get the right cartridge.
As I wrote, it is a 3/4 inch valve from the 1980's.

 

[Breplum]

grohemix 3/4 inch element , aka thermostatic cartridge 270 25000 $225. to $270. terribly overpriced.