If I am correct this vacuum advance is for a 69 chrysler 440. Just bought a NOS with the part no 2875761 on it. (refer to parts manual text page 8-17). It's also stamped with 12L.
Let me know where you bought an after market replacement.
Yes, tucks under the top of that! All covers seem to be dead! Maybe somebody can make a reproduction. I still got the original trunk covers and the trunk well liner that's fixed with snaps where the top is mounted to (just under the back window), and tucks under the green horizontal bar on the...
Maybe this will help. http://www.forcbodiesonly.com/mopar-forum/showthread.php?1253-Wanted-plastic-back-seat-cover-69-chrysler-300-convertible/page2
The small hole in the middle of the green horizontal bar is to fit the cardboard trunk divider with 3 (or 4) clips.
What's wrong with me? What's wrong with you? This is a forum! Just take it as it is and have fun too so now and than. Don't take everything serious. And do not forget that what goes around comes around.