Yes, I know this is a tall order but just in case someone has a flatbed Macson travelling steady gathering rust & dust under a bench and is willing to part with it.

My Macson is a 1946 17" Flatbed machine - the travelling steadies for these are a bit different by being fitted to the cross slide dovetails.
I recently came across this photo and it is the first time I had seen one in relatively good detail to know what to look for.
20171022_8447_trav_steady.jpg
On my 17" machine the distance from the bottom of the steady to the centre of the horizontal adjusting pin would be 6.75".
Ray