Difference between convertible and sedan stub frames

This forum may have a nice picture forums.phpstack-1081784-3880776.cloudway...viewtopic.php?t=6292

I have a sheet that gives a bit more detail. I believe it was published in an earlier Newsletter. If you are interested I could scan it and email it to you.

Are the details(blueprints or something else) of the additional reinforcements defined anywhere (that is presently available) to allow updating an earlier frame? I don't consider the pictures in Josh's book to be adequate without some additional words of explanation. Has anyone made these updates ?

The Engineering Changes booklet published by Auburn-Cord- Duesenberg Club in July 1960 shows that the first phaeton frame with extra reinforcements and welding was 1937 Cord 1751 H, This fact is dated 1/27/37.

On p.127 of Josh's book "Cord 810/812 The Timeless Classics", 2 photos credited to Ron Irwin show 6 additional reinforcements added to the open car frames. My 36 810 phaeton doesn't appear too have any of these added reinforcements. At what point in the production were these phased in?
Another difference between the stub frames is the pads to attach the birdcage which my frame has. Are there any additional differences in the stub frames between the sedans and the open cars?