Help IDing the Suffix
 

Looking at buying a bfy 42 PO.8 with a curious suffix on the frame under the SN 5xxx.

Looks like an equal sign with a forward slash.

Thanks in advance.

Correction- Should read byf
 

Should read byf

Might be a buffed out "F".

x2 on the f

Yes it's absolutely an "f" a bit worn out

Thanks to all for the timely responses