High/low beam question

Always been curious, why on these old mopars the high beams are the middle headlights and the low beams are the outter ones?

Same as every other manufacturer...
My guess is it's because outers generally delineate width of the vehicle, and are the normal setting.
Handy for oncoming, maximum spread of light for the driver.
Also seems better-looking, but then again I've been familiar with it since around 1957 ...

The highs are both headlights but the lows are only the outers. The third prong on the connector is "high", the high bulb only has two prongs.

and for whatever reason, [i forget] it was popular in many regions to swap the highs and lows, low headlights being in the center, highs on the outside.

Hmmmm, I don't think the harness has the slack to do that. AND the headlight buckets are also specific to high/lo for some reason (they carry different p/n's).

Yes the cups are high and low bulb specific.