Ridge or no ridge deck lid?

Was put in the lid to strengthen them as Burnt mentioned. Started approx mid year 1971, IIRC.

The lids with out the ridge almost always have dents on the rounded rear portion from people slamming them closed. Especially if the latch came out of adjustment.

It was a line wide change for both Dusters and Demons. Early cars in both models had no ridge lids.