Ok. That is the only one I ever saw like that, so you're probably right about the guy not knowing it had been replaced.
You're right too about the length on those danas, and how well they fit under Ebodys. Mine was a 440 4spd super drag pac 4.10. Somewhere in it's life the rear was replaced with a b body short dana. And yes, there's room for big tires.
70 challenger R/T S/E 440 mag A833 4spd dana 3.55 hemi orange/blk vinyl top.