model 42

Question
QUESTION: have a model 42 420 for 61 years has one digit different serial number on the two sections...would this have been a mfg mistake...I am the only one that has fired it since my 13th birthday 61 years ago

ANSWER: Without a manufacturers name I can't you anything.

---------- FOLLOW-UP ----------

QUESTION: this is a winchester model 42 410 pump....it seems to me the mfg got two guns in sequence and interchange them,giving me a gun with different serial number on each part making another gun some place to have the same problem....could this be right?

Answer
In general there only one serial number on a gun.
Takedown models had one the reciever and one on barrel assembly.
They should be the same number.
Its either a mistake at the time of manufacture or 2 guns combined as a repair later.
These guns are highly collectable. They worth $250 to $8000 depending on condition
and exact submodel. Get your gun appraised by a gunsmith.
I would also contact Winchester about a factory letter.
Cody Museum has most of the older records.
307-587-4771