The piece with the 2 rods, clamp and knob is part of a surface gauge. I can not identify the brand as it is a machinist tool and if not branded could very well be shop made or Chinese. I would say judging by the age it is likely shop made, unless there is a name on it. E.g. Starrett, Fowler, TCI, etc. The all thread and wing nuts can be purchased at any hardware store. So there is nothing special about them. As for the flat plates I am clueless. There is a possibility that the threaded rod and wingnuts were use in conjunction with them, But i can not affirm that. All I can say for certain is the part of a surface gauge does not belong with any thing pictured. You can take my word for this, I am a machinist.

The piece with the 2 rods, clamp and knob is part of a surface gauge. I can not identify the brand as it is a machinist tool and if not branded could very well be shop made or Chinese. I would say judging by the age it is likely shop made, unless there is a name on it. E.g. Starrett, Fowler, TCI, etc. The all thread and wing nuts can be purchased at any hardware store. So there is nothing special about them. As for the flat plates I am clueless. There is a possibility that the threaded rod and wingnuts were use in conjunction with them, But i can not affirm that. All I can say for certain is the part of a surface gauge does not belong with any thing pictured. You can take my word for this, I am a machinist.

References:

https://www.zoro.com/starrett-surface-gage-3x2-916-in-516-dia-9-in-l-57a/i/G3...