The image below is of the Special Warfare Armoured Transport or Special Warfare Assault Transport (SWAT*) by Chrysler from 1962. As far as I can tell this is the only image of it.
This vehicle was ready to roll and would have been fully through development by the beginning of the US-Vietnam War.
A few features to note:
- That's not the T50 turret from Cadillac Gage, that was designed later. What it actually is is anyone's guess.
- It swam via wheel movement.
This would look great in a what-if Vietnam scenario, covered in dust and festooned with period equipment.
(*Despite the name it doesn't seem to have been aimed at police use, this wasn't done at that time)