Doug,
I believe all 28 and early 29 phaetons had curtain trays mounted under the rear floorboard and part of the tray under the front seat pan. There were two alignments for the under the rear floorboard trays I stumbled onto when I was trying to install my early 29 tray. I had nothing left of the tray except the hinge holes and the mounting holes in the rear side of the body crossmember. Early 28's have the rear end of the curtain tray mounted to the front of the body crossmember located under the front of the back seat. Sometime in mid 28, I believe, Ford, for some reason, shifted the rear end of the tray to mount on the rear flange of the same body crossmember. I am not really sure when Ford switched from under the car tray to under the front seat, but an educated guess would be sometime in March or April of 1929. Of course, by that time there were lots of plants making model A's so there must have be a pretty wide range of dates for the switch over. I suspect the Detroit plant probably switched over sometime in February or early March with other more remote plants not switching until late April and maybe even in May sometime. Again these are my thoughts after investigating the curtain tray subject when installing the tray in my car.
Rusty Nelson