Actually all parts of all Lancaster Mks had the 683 prefix. Here there is the 57 one. What is more the round inspection stamps with the FM ### format indicate the Fairey factory rather than the Avro that used the R generally ( R3 or RY in oval ring). However the factory stamp of the R2 ## or R2 xx format but in a circle was used for the Halifax by the Rootes Securities factory .
IMHO the part numbers indicate the Halifax ( Mk.I ... IIRC ) but not the Lancaster. What is more the B letter of the part numbers indicates the wings, ailerons and flaps sections. Usually the digits after the letter indicated the aircraft side. The odd numbers were for the port side while the even ones for the straboard. All of them are the odd numbers. So the panel/piece may come from the port wing.
For example ...
57697 B15 = 57- Halifax airframe, drawings number 697, B = wings, ailerons and flaps, 15
57619 B33 = 57- Halifax airframe, drawings number 619, B = wings, ailerons and flaps, 33
57600 B49 = 57- Halifax airframe, drawings number 600, B = wings, ailerons and flaps, 49