Help Needed Decoding a GM PartsWiki List

[Gromit]

Need help understanding something about the structure or design of those archived GM Parts lists that are available on gmpartswiki dot com (Which are excellent by the way)..

Please see image of one such page attached from a 1970 Chevy Truck steering column parts list.

For example, looking at the parts group 4.012; the first part is #3873136; "Control Lever Housing"

There is no confusion there of course - that part is obviously for a 1966 Series 20 (except D-D)

But what about the second part number (#3902564).

Does the list of other vehicle types above that number go with the first part number or the second?

Because if you look closely, there is no comma after the first vehicle description, but there are commas after the following vehicle descriptions, implying that they would go with the second part number.

But the other way would make sense too; as in; why not list the part and then all the vehicles...Hopefully I am not the only one confused

In other words, does the 1967 Series 10-20 (exc. D-D) use a #3873136 Control Lever Housing, or does it use a #3902564 Control Lever Housing?

By the way, I have no idea what a "D-D" is that they refer to; though I'm pretty sure that they don't mean "Daily Driver"