870 not typical for serial number range?

[faithfarms]

not an expert but sounds like you are correct in your assumption. Wood could have been damaged or someone liked the later model wood.

[HeWhoHunts]

Does the forearm have "diamond shaped" style checkering with finger grooves? Is there a "duck" on the pistol grip cap? If so, it could be original but an ADL model. Barrel has been changed of course. Im looking for info on how to tell and ADL from a BDL in another question here.

Nice old guns. I love em!