It's a spreader, not tensioner. Trying to figure out what it is used on though. @red55, you gonna give us a hint?
I have discovered what this is, however it is too good to answer right now. Gotta get this thread going again.
It's too shiny to be used in a trench. So, if it's a spreader/adjuster, what the $#%$%^ is the object that sits in those rectangular grooves? Well, there's an answer in there.......(If the object is 3-4 inches in width, I could use it as a rib spreader......in an emergency, of course.....) {{thinking}}
Think about it. What is about four feet, 8 inches wide and has an essential need to maintain a proper gauge and has a T-shaped top?
I concur. Red's addition of the dimensional width gave it up: the width of two horses' asses, side by side! http://www.naciente.com/essay94.htm