There is a lot of misinformation about Textured Argent paint, much of which is complicated by the seemingly endless shades of Textured Argent being offered by vendors selling it as "correct". I've seen a few shades being offered that (IMO) best match the factory shade. However, I haven't seen any I'd call a 100% perfect match, which I don't think is really possible due to the different paint componants available these days as compared to the obsolete componants of the 70's.
The first use of Dark Textured Argent was in the mid 60's for tail panel and headlamp door detail paint (67 &68 GTX's, etc.). The same formula was used up into the 70's. Light Textured Argent was also used during the same period for various applications.
1970 Cuda Grilles & Shaker Bubbles, as well as 71 Cuda Grilles (that were'nt painted body color) and Rallye Wheel Center caps were all Dark Textured Argent. 70 Rallye Wheel centers were the Light Textured Argent. So, yes, Dark was used both years on various componants.
The best Matches to either I've seen are Alltrim Specialties NOS blend (some original NOS componants mixed with some modern componants) I do not believe Alltrim sells paint, just restoration services. Frank Badelsons sells paint, it's an excellent product and a great match. I've heard BE&A also offers a nice match but I don't know if they sell it or just the restoration service (I've never seen BE&A's in person).
The bubble above was painted with NOS Dark Textured Argent.
