Leupold scope base mount ID help

Part # 42999K. Response from Leupold pending for a week+. Many thanks for input. See pics.Attachment 323049Attachment 323050Attachment 323049Attachment 323050

I'm not sure that's a Leupold part number. What is the hole spacing? Is there any faint engraving on the bottom that might be a clue? Is the rear radiused or flat?

Need more information. What's this going on, and what kind of help do you need?

I picked this up as part of a larger purchase. Would like to know what it is before I get rid of it. Just noticed box is marked 37703, possibly a part number.