Door latch confusion

Hi everyone. I was taking about the window regulators on my '69 Barracuda. While they were out, I've been replacing the lock cylinders too. The passenger's side was easy, but I couldn't get the driver's side to sit flush - it's like the handle mechanism was blocking it. To make a long story short, I think at some point someone put the wrong handle on my Barracuda, or butchered a factory one. I'll let the pics explain:

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First is my passenger's side door. This looks fine, and has a big Z-shaped rod that goes from the handle to the latch. The button is black and works normally.
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This one is the driver's side. The handle internals interfere with the lock cylinder, and it's connected with a thin rod. The handle is also missing any sort of spring and doesn't return when you press it. The driver's side striker has been out since I bought the car, so I didn't realize until now that the handle didn't work. Also, this one is a chrome button.

It would seem that I need to get another handle (and maybe a latch too; it's a bit frozen). My question is - what's the deal with the two different linkage bars? can I get the thicker one anywhere and will it work on the existing (or a new) latch? Or are they supposed to be different on the drivers and passenger side?