Who knows what about early 8-3/4s?
I don't see those housing ends and axles as a factory mopar passenger car. The factory tapered axles are smooth with a key way like a crank snout, then the threaded end. These axles have splines. Factory axle housing flanges have 5 holes for the brakes, these have 6 holes.
Look at the housing you can see a step down where they welded this stuff on.
I don't have any knowledge of a pickup truck tapered axle 8.75