Sweet.
The more I look through the file, the more I scored. He gave me 2 or 3 Yanmar dealer advertisements, one is a 3 page folder in full color detailing all the implements and all the features of the 142 and 146. Really, really nice stuff.
I want to try to scan the full color brouchure and post it here if I can.
There is no mention of any of the YM12X series tractors in any of my literature, indicating that Yanmar did not consider them "connected" enough to place them in the same adverts. They share almost everything in common as far as chassis drivetrain (except engine) and sheetmetal goes, but my guess is they were just the lower priced option with its own marketing (or maybe none?).
Hopefully I get all three tractors together at some point this week and snap some photos of them together.