I think it's light but...the spray can argents on the market are way too light. Roger Gibson sells the correct argent for the earlier Cuda shaker bubbles and grills. I assume the 74 used the same shade. The factory argent really changes color in different lighting. I've seen pictures of the light argent that looks very dark. It would be very easy to mistake it for the dark argent.
The RG paint is very expensive. If you are building a nice driver, you can get close by mixing the two(light/dark) paints that Totally Auto sells. I've seen some people use Totally Auto's dark argent on the Cuda grill and it looks too dark. It does look good, but it looks a little too dark. You can spray the light argent over the dark argent to get a color in between the two. That's what was done on my Challenger tail light housings.