I thought M70 or Springfield?
It's 3 3/8" long. The Mauser is 4 1/4"

Springfield 03A3; most early 03s have a little gas hole in them.
No Mauser is that short.

It's likely from a cut-down mauser 98. I have seen this done more than once. Look closely for evidence of a weld.

No, definitely not that.
Look at the nose of it, where the extractor rides in the bolt groove; the 98 Mauser has about 3/8ths inch between the groove and the bolt face.
A 93 Mauser, and the Springfield 03 derived from that, has less than 1/4 inch. The picture clearly shows the difference.
So, the extractor in the picture is not a 98. It is an 03 Springfield, and further, made after they stopped putting the gas escape hole in them, which was during WW2.
Another clue is the way the claw is beveled to snap over a round in the chamber; a design feature of the 03, so as to allow single loading and to make use of the magazine cut off; Mausers are designed for clip loading only.

Not Mauser , it would hit the bolt guide rib on a 98 and 91-95 sr have recessed extractors , ( not the same height on the outside )

Pretty sure Springfield.

I found more parts in a box with a receipt marked New Cumberland Army Depo

It would not fit on a 98 at all due to the groove geometry I mentioned above, and they do work well on earlier Mausers; the recessed height is not important to anything. I have one on a Swede 96 right now. (I notched the guide rib, also not germane to it's fit otherwise. )
Not pretty sure; definitely, 03.