Are there any casting numbers seen on the gun mount or mantlet of the ISU-122S ?, (point me to a picture?)

I know they are seen on the mount of (some) ISU-122/152s, but have not been able to find any clear images of a 122S ?

and as a follow up is the casting number on the 122/152 a factory specific thing as only some seem to have them ? Or will they be present on all, just covered in decades of overpainting/rust on some of the surviving examples?