Here are the early TB30 tabs, circa 1970.
You can see the application then was 1964-67 Chevelle only.
Here is the later design, circa 1973.
Now listed for both the Chevell AND GTO!
Here are a set of NOS TB30 tabs I bought which are the later design. Note on the drawing that they must have continued to use the instructions for the early TB30 tabs for the later ones.
These tabs here were made by another fellow, Dan R. and are exact duplicates to the later TB30 design. The orange he uses is a nice match to some of the original NOS items I have, such as the battery/weight box (which I'll try to get a picture up here later). As you can see from the one set of tow hubs above, it looks about right for a match.
I do not beleive the burnt orange ones I have is a primer to be painted over, as they are actually quite glossy. I think it is just as Plowman reported. NMW did use different paints, somewhat influenced by what was available to them at the time they needed more paint.
Does anyone have a picture of any early TB30's or maybe even lucky enough to own a pair?