FOK back door vs standard Mills back door

[sam2002]

Did these doors take locks of different circumference ? I have one original fok back door seems to take a smaller yale lock and a reproduction fok back door that will take a standard mills worm cut key lock .any comments ?
Sam

[mrslot1]

Hi Sam,
yes some of the early mills FOK doors took the early Yale lock before it became standard for mills to use the Bell lock.
some early FOK's even had a wood centre for the back door, and just a metal frame around,

thanks Dave