I've never seen literature calling out anything other than a TB1 and what I've seen is they are all the same width. BUT remember that NMW was not the only game in town as Lakwood also made them, possibly others.
My Pop did have what we both agreed was an NMW bar that seemed to be unmodified and original that WAS wider than the standaard bar. Eventually we sold it to a friend who modified it down to the standard width. I don't know the story on this. We thought maybe for an Impala but who really knows? Just wanted to share the fact that we've seen variations in width.