That's NOT an O.E.M. SMV bracket. (That was made from 1"X1" angle iron. ) It well could be that's what it was used for though. It appears to be a "factory made" bracket as opposed to "farmer made". Gonna have to dwell on that one a bit..............
POSSIBLY some sort of umbrella or sunshade mounting point. Also good chance of being for remote hydraulic outlets.
I seem to recall some sort of arraingment simular to that for attaching lines (rope) to control row markers on a corn planter????? (Massey or Cole????)
Didn't you buy this tractor from someone who used it as an orchard tractor? Maybe some sort of sprayer control mounting point? Also, some "bog disc's" had rope controls to angle and "un-angle" them. Maybe something for that?
Again, this one's got my curiousity up. I've got a pamphlet from Massey (printed in 1970) that shows all the options and accessories available for their tractor line. When I get home, I'll look through it to see if it's part of anything Massey sold.