They were all designed and built to base model which was bench seat, column shift. The floor pans got drilling, cutting, and welding for any option including bucket seats. And back to the topic... With some measuring you will find the engine is dang near 3 inches right of center, annnnnd this offset fades back to center of the body by the time you reach the differential. Anyway... now grab a framing square and study. Which way would they need to shift the differential to get it closer to square with the rest of the drive line? ( shift the left end forward or right end rearward could work? ).
Every mfgr does these things differently. Like Ford differentials having one axle shorter than the other for example.
So why weren't these Chrysler bodies designed to this offset? Couldn't they shift one or both wheel wells so wheel sits dead center of both? I don't know. I imagine such an offset could echo throughout the build. One rear passenger has more leg room than the other? LOL
We could all go out and measure our a-bodies to verify this offset.
We'll never see one case where the long side was moved forward for any reason.
We often see the short side moved rearward and most cases its for larger that OEM tires.