The tabs are at the lip where it folds over onto the inner structure. That was how the skin was attached at the back. Here's a pic of mine. You can can barely see 2 tabs peaking out from under the burn blanket. In your original pic, I see the raised area of 2 on yours, but they aren't as defined because of sealer and paint.
My lid is an over the counter replacement from a very early crash repair and has no date stamp either. My lid looks identical to your pics. I did find what may be an inspector stamp of "L" on 1 rib of the bottom side, but that is all.
