Yes, I think I agree Lloyd... the AMK catalog did not show availability on the correct bolt (with captive washer). And based on the orientation shown for the hardware in the AIM (bolt in from the bottom thru the spoiler first), the AMK kit has the captive washer on the side which least needs it, and nada on the side needing it (thru the spoiler itself).
After this discussion, I need to check my spoiler hardware which should be in a bag somewhere..
.. I know I bought a new spoiler from GM in the mid 70's after buying the car, but I don't recall buying hardware, so there's no telling what I have....
Noting also that the AMK kit includes the bolts/washers/nuts for the braces as well.. accounting for the 28 included pieces.
I didn't find a photo for the G-4320 kit..... is it because I don't know where to look?