What's with these differences in OEM 69-72 steering wheels? Repro for comparison.

[DeadheadNM]

Curious about the 69-72 steering wheel configurations and part numbers. Looks like the early or period GM wheels had part #9749753. These wheels had threaded holes emerging from the backside of the hub for horn mount hardware and a steering wheel puller (first pic attached).

Later run GM wheels had part #335212 and lacked at least the threaded holes for the wheel puller (see second pic). The reproduction steering wheel (third pic) has all the holes of the early/contemporary run.

The last pic is of an OEM wheel but it lacks threaded holes in the backside of the hub for the puller and horn mount hardware all together (don't have part number). To the detail freaks who care about such minutia like me: what's the story? Differences in manufacturing plants? Change in manufacturing design or die over time?