On the side inside or on the toplid inside

On the soundboard - behind the action on the left side.

On very old Feurich pianos, without a fully braced plate you may find the number also here pressed into the Pinblock.

Also you should find mostly the number on the soundboard on the backside of the piano.

The aga of each Feurich piano can be defined by the instrument number. Here you find the different positions on the piano where the instrument numbers have been fixed in the past.

This grafic shows you the numbers and the years in which they had been made - give it a click