Can anyone identify this mystery tool?

[AlD]

This one has me stumped. I bought it along with a bunch of other machinist stuff from an estate, t's an SPI, so it is definitely for a machine shop, and the model number is 98-040-9. A Google search turned up nothing.
It has what looks like a holddown on the base, and I think it might attach to the bed of a lathe or some such, which led me to believe it might be some sort of indicator holder--but I'd like to find out for sure. Anyone out there in Garagejournalland seen this thing?

Thanks in advance, guys.
Al D.

 

[454ragtop]

Does the rod held in with 2 knobs/screws have a diamond in the end? Thinking its a diamond for use on a surface grinder?

 

[lilredex]

A work stop.

http://www.lostcreekmachine.com/images/SPIworkstop.jpg

http://www.lostcreekmachine.com/vises_rotabs_sineplates.htm

 

[Techie1961]

Yup, looks like a work stop for a vise on a milling machine. Allows you to do multiple pieces at the same position.

 

[AlD]

Bingo--a work stop! Thanks so much.
Al