What is this terminal connector called and where do I find some?

Packard 56 Male terminals seem to be as close as can be readily found to the original Chrysler.
Packard Electric Division became Delphi and now Aptiv, but the stampings are the same.

There's a number of subtle differences between the different versions out there.
Original '66 - '67. This insulation I patched with liquid electrical tape and a wrap of brown tape.
upload_2020-8-9_9-35-8.png
upload_2020-8-9_9-37-37.png
Originals are stamped G and sx.

Here's a photo of the ones that came on a recent M & H reproduction harness next to loose terminals purchased from Waytek Wire.
upload_2020-8-9_9-43-7.png

and a 12 ga version (left) without the back guide/support wings
upload_2020-8-9_9-44-10.png

Notice that these are little shorter both in the crimp lengths and the tab than the ones M & H used.

The ones M & H and Evans use are a little closer to the original length.

Packard (PED) used by M&H and original Chrysler
upload_2020-8-9_9-55-33.pngupload_2020-8-9_9-56-21.png

Installed with with a good open barrel crimper, you'll do fine.
The one toolmanmike suggests in this thread is relatively inexpensive,
Lets Talk Open Barrel Crimpers - Reviews and Discussion

Female terminals discussed here.
Sources for Chrysler type wire terminals