Ah, man.. Need help from a 65 GS expert right about now.

Body-to-frame rubber mounts.
Ordered up a complete set for 65 GTO from Ames Pontiac.
Figured they were the same, and a good source for the right stuff.
Now I'm not so sure...
Are the GTO and our GS different?
Or are we just dealing with what the aftermarket has to offer us now?
Where to get correct rubber mounts?
The factory-replica bolts and big flat washers from Ames are lovely.
But check out this weirdness with the mounts near the rear axle (pic1).
There are captive nuts welded inside the support rails under the body there (pic2).
Rubber mounts are just flat on top and don't have bolts into these nuts (pic3)
The body just sits on these - even though there's a place for bolts?

The Ames mounts are pretty good quality it seems.
And while it's hard to tell if they are correct or not because the originals are all squooshed,
I'm thinking maybe they can be made to work?
Perhaps it's an upgrade to actually have these mounts near the rear end actually bolt up?
Ugh.
Here i was all stoked to get the good stuff and have it just work,
but they're so different than what i removed.
Let me know if any of you guys have crossed this bridge before.
Please and thanks,
Steve