I can believe the rubber washers were for either rain water sealing or vibration isolation.
The larger holes certainly had the hoses with grommets for the Delaney Gallay heater, and presumably could have been for whatever heater may have been previously there.
I decided to remove the battery tray, which was quite obviously not original. I think Peter S pointed that out some months ago.
And I find more holes. And the obvious reason the battery tray was replaced. There is insufficient support under the battery and the vibration of that weight caused the metal to fatigue and tear.
I now have 45 holes to fill, and 3 long tears caused by the weight of the battery.
So it raises a new question. What was there originally?
I saw three strengthening pieces welded underneath, two of which have threaded inserts such as I have seen on door window winding mechanisms. They are 1/4-26 BSF thread.
I ran a tap through them and stuck a couple of bolts in them.
Also what looked like an L brace along the front that was bent over to fit the tray, so I straightened it up.
I’m thinking these threaded inserts were originally for holding down the battery, and the third piece with a larger hole was where the battery ground cable was originally attached.
Does that seem right to you all? Were there L braces on all sides of the battery? The tray I removed, those 3 L braces are riveted to the main panel. Could that have been cut from another donor car?