Early top bow pivots (A2901).
I have one early GPW pivot, and one MB. Both are marked with the part number along the edge, and have 5/16 NF thread for the thumb screw. You can just see the GPW part number along the edge on this picture. I am looking to swap this GPW one for for an early MB one with the A2901 part number along the edge, and 5/16 NF threads if somebody is intrested. I think this one came off a MB/GPW from Norway in about 1990.
Here is the early style MB pivot I am looking for… will swap for early GPW one that I have, GPW one is not for sale.