So prior to 1968 they didn't need serial numbers.  Traded for an old 16 gauge 870 with no serial number anywhere on it, but what appears to be a serial number is hand scribed onto the trigger guard.  

The question is, can I trade out the trigger guard and still be legal, or since the serial number appears to have been placed there, do I need to keep the trigger guard with it?

Gun was not sold through an FFL but from a private party, so I have no way of knowing if this actually IS a serial number or just a personally applied number the way my dad used to engrave his USMC ID onto things.

Thanks for the information.

A serial number must be on the receiver or the part of the gun that is considered a firearm.

A serial number would not be on the fire control group (trigger assembly).

There is nothing illegal about a firearm with no serial number made prior to 1968 under Federal law.

There might be state laws in states that require registration that will not register a firearm that never had a serial number.

More likely that is someone's driver's license # or part of their social surveillance # that was scribed onto the trigger guard as a theft deterrent/identification

Sweet, now to either restore the trigger guard or find a replacement to swap it out with.  I think 12 and 16 used the same size, so there should be plenty of donors out there.  

Pre-68 Remington 870s still had serial numbers from the factory. Might want to find out what happened to yours...

Here's a KA (may-1954) barrel coded 870. Note serial number under Remington

This.

The 870s always had a serial number.

The 12/16 trigger housing is the same, but I think the carrier was unique to the 16 gauge.

Ok, I'm just blind.  The serial number IS there, just wasn't where I expected it to be and my mind kept glossing over that it WAS the serial number as it looked like part of the "Remington"

Sorry to waste everyone's time.  

And it IS a different number than the one on the trigger guard.