Excellent photos JD. That last one is a 318 mount. The one in my photo is an original 1966 A Body 273 mount, and I had my 360 in the Vart with the original 273 mounts for many years - and will again if I ever get the sucker off the rotisserie. :)
We got a little off topic on this thread.
There is actually 2 topic's we are now discussing,early A and later A-body's.
I may have had a part in it.It was not intentional,my bad.
But if we are talking 273/318 mounts vs 340/360 mounts,my info speaks for itself.
Hopefully everybody's info will be able to help in the long run.