I think that oil fill road draft tubes were used only on the earliest 216s in cars - pre '41. But I think that the truck engines always had them:


Some guys use the road draft tube hole for a PCV conversion:
with this setup one could still pop the PCV to fill the crank case.

And I have also seen the non-filler road draft tubes modified by cutting off the down tube - welding bung over the hole so that a PCV valve can then be fitted to the up tube. This is similar to the GM dealer installed option.

So there can be competing interests for the same opening(s) . . .